Method and device for transmitting user data through random access response message in mobile communication system

ABSTRACT

The present disclosure relates to a communication method and system for converging a 5 th -Generation (5G) communication system for supporting higher data rates beyond a 4 th -Generation (4G) system with a technology for Internet of Things (IoT). The present disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. The present invention provides a method and a device for efficiently transmitting user data through a random access response message in a mobile communication system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a 371 National Stage of International ApplicationNo. PCT/KR2019/017181, filed Dec. 6, 2019, which claims priority toKorean Patent Application No. 10-2018-0156299, filed Dec. 6, 2018, andKorean Patent Application No. 10-2019-0076660, filed Jun. 26, 2019, thedisclosures of which are herein incorporated by reference in theirentirety.

BACKGROUND 1. Field

The disclosure relates to a method and a device for efficientlytransmitting user data through a random access response message in amobile communication system.

2. Description of Related Art

To meet the demand for wireless data traffic having increased sincedeployment of 4G communication systems, efforts have been made todevelop an improved 5G or pre-5G communication system. Therefore, the 5Gor pre-5G communication system is also called a “Beyond 4G Network” or a“Post LTE System”. The 5G communication system is considered to beimplemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, soas to accomplish higher data rates. To decrease propagation loss of theradio waves and increase the transmission distance, the beamforming,massive multiple-input multiple-output (MIMO), full dimensional MIMO(FD-MIMO), array antenna, an analog beam forming, large scale antennatechniques are discussed in 5G communication systems. In addition, in 5Gcommunication systems, development for system network improvement isunder way based on advanced small cells, cloud radio access networks(RANs), ultra-dense networks, device-to-device (D2D) communication,wireless backhaul, moving network, cooperative communication,coordinated multi-points (CoMP), reception-end interference cancellationand the like. In the 5G system, hybrid FSK and QAM modulation (FQAM) andsliding window superposition coding (SWSC) as an advanced codingmodulation (ACM), and filter bank multi carrier (FBMC), non-orthogonalmultiple access (NOMA), and sparse code multiple access (SCMA) as anadvanced access technology have also been developed.

The Internet, which is a human centered connectivity network wherehumans generate and consume information, is now evolving to the Internetof things (IoT) where distributed entities, such as things, exchange andprocess information without human intervention. The Internet ofeverything (IoE), which is a combination of the IoT technology and thebig data processing technology through connection with a cloud server,has emerged. As technology elements, such as “sensing technology”,“wired/wireless communication and network infrastructure”, “serviceinterface technology”, and “security technology” have been demanded forIoT implementation, a sensor network, a machine-to-machine (M2M)communication, machine type communication (MTC), and so forth have beenrecently researched. Such an IoT environment may provide intelligentInternet technology services that create a new value to human life bycollecting and analyzing data generated among connected things. IoT maybe applied to a variety of fields including smart home, smart building,smart city, smart car or connected cars, smart grid, health care, smartappliances and advanced medical services through convergence andcombination between existing information technology (IT) and variousindustrial applications.

In line with this, various attempts have been made to apply 5Gcommunication systems to IoT networks. For example, technologies such asa sensor network, machine type communication (MTC), andmachine-to-machine (M2M) communication may be implemented bybeamforming, MIMO, and array antennas. Application of a cloud radioaccess network (RAN) as the above-described big data processingtechnology may also be considered an example of convergence of the 5Gtechnology with the IoT technology.

In line with the recent development of mobile communication systems,there is a need for a method and a device for efficiently transmittinguser data through a random access response message. In addition, amethod and a device for efficiently performing cell reselection of aterminal according to the same frequency priority are required in amobile communication system.

SUMMARY

The disclosure proposes a method and a device for efficientlytransmitting user data through a random access response message in amobile communication system.

In addition, the disclosure proposes a method and a device forefficiently performing cell reselection of a terminal according to thesame frequency priority in a mobile communication system.

In order to solve the problems described above, the disclosure providesa method of processing a control signal in a wireless communicationsystem, which includes: receiving a first control signal transmittedfrom a base station; processing the received first control signal; andtransmitting a second control signal generated based on the processingto the base station.

In order to solve the problems described above, the disclosure providesa method of operating a terminal in a wireless communication system,which includes: receiving a paging message including a dedicatedpreamble from a base station; transmitting the dedicated preamble to thebase station, based on the paging message; receiving a random accessresponse (RAR) message from the base station, based on the dedicatedpreamble; if there is user data related to downlink early datatransmission (DL EDT) in a non-access-stratum (NAS) container includedin the received RAR message, decoding the user data from the NAScontainer; and inserting the user data into the msg3 and transmittingthe same to the base station.

In some embodiments, the method further includes transmitting, to thebase station, UE capability information including an indicatorindicating whether or not to support DL EDT using RAR.

In some embodiments, the method further includes receiving a physicaldownlink control channel (PDCCH) to which a separate radio networktemporary identity (RNTI) is applied, and the separate RNTI indicatesthat the paging message is configured as only the user data related toDL EDT.

In some embodiments, a subheader related to the DL EDT, which isincluded in the RAR message, is located after subheaders that are notrelated to the DL EDT.

In another embodiment of the disclosure, a method of operating a basestation in a wireless communication system includes: receiving a pagingincluding user data from a mobility management entity (MME);transmitting a paging message including a dedicated preamble to aterminal; receiving the dedicated preamble from the terminal, based onthe paging message; transmitting a random access response (RAR) messageto the terminal, based on the dedicated preamble; and receiving msg3from the terminal, wherein if there is user data related to downlinkearly data transmission (DL EDT) in a non-access-stratum (NAS) containerincluded in the RAR message, the user data is decoded by the terminal,and wherein the decoded user data is inserted into the msg3.

In another embodiment of the disclosure, a terminal includes: atransceiver capable of transmitting and receiving at least one signal;and a controller connected to the transceiver, wherein the controller isconfigured to receive a paging message including a dedicated preamblefrom a base station, transmit the dedicated preamble to the basestation, based on the paging message, receive a random access response(RAR) message from the base station, based on the dedicated preamble, ifthere is user data related to downlink early data transmission (DL EDT)in a non-access-stratum (NAS) container included in the received RARmessage, decode the user data from the NAS container, insert the userdata into the msg3, and transmit the same to the base station.

In another embodiment of the disclosure, a base station includes: atransceiver capable of transmitting and receiving at least one signal;and a controller connected to the transceiver, wherein the controller isconfigured to receive a paging including user data from a mobilitymanagement entity (MME), transmit a paging message including a dedicatedpreamble to a terminal, receive the dedicated preamble from theterminal, based on the paging message, transmit a random access response(RAR) message to the terminal, based on the dedicated preamble, andreceive msg3 from the terminal, wherein if there is user data related todownlink early data transmission (DL EDT) in a non-access-stratum (NAS)container included in the RAR message, the user data is decoded by theterminal, and wherein the decoded user data is inserted into the msg3.

According to an embodiment of the disclosure, it is possible toefficiently transmit user data through a random access response messagein a mobile communication system.

According to another embodiment of the disclosure, it is possible toefficiently perform cell reselection of a terminal according to the samefrequency priority in a mobile communication system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a diagram illustrating the structure of an LTE system towhich the disclosure is applied.

FIG. 1B is a diagram illustrating a radio protocol structure in an LTEsystem to which the disclosure is applied.

FIG. 1C is a diagram illustrating a random access process in thedisclosure.

FIG. 1D is a flowchart illustrating a process of including user data ina random access response message and transmitting the same in thedisclosure.

FIG. 1E is a diagram illustrating the configuration of a random accessresponse message that does not contain user data in the disclosure.

FIGS. 1FA and 1FB are diagrams illustrating the configuration of arandom access response message containing user data in the disclosure.

FIG. 1G is a flowchart illustrates the operation of a terminal in thedisclosure.

FIG. 1H is a flowchart illustrating the operation of a base station inthe disclosure.

FIG. 1I is a flowchart illustrating the operation of an MME in thedisclosure.

FIG. 1J is a block diagram illustrating an internal structure of aterminal to which the disclosure is applied.

FIG. 1K is a block diagram illustrating the configuration of a basestation according to the disclosure.

FIG. 1L is a diagram illustrating the configuration of a random accessresponse message containing an RAR subheader having a field L and an RARhaving a size L in the disclosure.

FIG. 1M is a diagram illustrating the configuration of an RAR subheaderincluding a field L in the disclosure.

FIG. 1N is a diagram illustrating the configuration of a MAC RARincluding a NAS container in the disclosure.

FIG. 1O is a flowchart illustrating the operation of a terminal in thedisclosure.

FIG. 1P is a flowchart illustrating the operation of a base station inthe disclosure.

FIG. 2A is a diagram illustrating the structure of an LTE systemaccording to an embodiment of the disclosure.

FIG. 2B is a diagram illustrating a radio protocol structure in an LTEsystem according to an embodiment of the disclosure.

FIG. 2C is a diagram illustrating the structure of a next-generationmobile communication system according to an embodiment of thedisclosure.

FIG. 2D is a diagram illustrating a radio protocol structure of anext-generation mobile communication system according to an embodimentof the disclosure.

FIG. 2E is a diagram illustrating a procedure in which a base stationreleases a connection of a terminal so that the terminal switches froman RRC connected mode to an RRC idle mode and a procedure in which aterminal establishes a connection with a base station to then switchfrom an RRC idle mode to an RRC connected mode according to anembodiment of the disclosure.

FIG. 2F is a diagram illustrating a procedure in which a base stationreleases a connection of a terminal so that the terminal switches froman RRC connected mode to an RRC inactive mode and a procedure in which aterminal establishes a connection with a base station to then switchfrom an RRC inactive mode to an RRC connected mode according to anembodiment of the disclosure.

FIG. 2G is a diagram illustrating a process of reselecting a cell when aterminal is in an RRC idle mode or an RRC inactive mode according to anembodiment of the disclosure.

FIGS. 2HA and 2HB are diagrams illustrating a process of reselecting anintra-frequency/inter-frequency cell having the same priority as thefrequency of a serving cell when a terminal is in an RRC idle mode or anRRC inactive mode according to an embodiment of the disclosure.

FIG. 2I is a block diagram illustrating an internal structure of aterminal according to an embodiment of the disclosure.

FIG. 2J is a block diagram illustrating the configuration of an NR basestation according to an embodiment of the disclosure.

DETAILED DESCRIPTION

Hereinafter, embodiments of the disclosure will be described in detailin conjunction with the accompanying drawings. In the followingdescription of the disclosure, a detailed description of known functionsor configurations incorporated herein will be omitted when it may makethe subject matter of the disclosure unnecessarily unclear. The termswhich will be described below are terms defined in consideration of thefunctions in the disclosure, and may be different according to users,intentions of the users, or customs. Therefore, the definitions of theterms should be made based on the contents throughout the specification.

The advantages and features of the disclosure and ways to achieve themwill be apparent by making reference to embodiments as described belowin detail in conjunction with the accompanying drawings. However, thedisclosure is not limited to the embodiments set forth below, but may beimplemented in various different forms. The following embodiments areprovided only to completely disclose the disclosure and inform thoseskilled in the art of the scope of the disclosure, and the disclosure isdefined only by the scope of the appended claims. Throughout thespecification, the same or like reference numerals designate the same orlike elements.

First Embodiment

In the following description of the disclosure, a detailed descriptionof known functions or configurations incorporated herein will be omittedwhen it may make the subject matter of the disclosure unnecessarilyunclear. Hereinafter, embodiments of the disclosure will be describedwith reference to the accompanying drawings. Although the disclosure isprovided based on an LTE system, the disclosure may also be applied toother mobile communication systems such as NR, which is anext-generation mobile communication system, and the like. For example,in the disclosure, an evolved NodeB (eNB) in LTE corresponds to anext-generation NodeB (gNB) in NR, and a mobility management entity(MME) in LTE corresponds to an access management function (AMF) in NR.

FIG. 1A is a diagram illustrating the structure of an LTE system towhich the disclosure is applied.

Referring to FIG. 1A, a radio access network of an LTE system includesEvolved Node Bs (hereinafter referred to as “ENBs”, “Node Bs”, or “basestations”) 1 a-05, 1 a-10, 1 a-15, and 1 a-20, a mobility managemententity (MME) 1 a-25, and a serving-gateway (S-GW) 1 a-30, as shown inthe drawing. User equipment (hereinafter referred to as “UE” or“terminal”) 1 a-35 accesses an external network through the ENBs 1 a-05to 1 a-20 and the S-GW 1 a-30.

In FIG. 1A, the ENBs 1 a-05 to 1 a-20 correspond to existing node Bs ina UMTS system. The ENB is connected to the UE 1 a-35 through a wirelesschannel and performs a more complex role than the existing node B. Inthe LTE system, since all user traffic including real-time services,such as VoIP (Voice over IP) through Internet protocol, is servedthrough a shared channel, a device for collecting status information,such as buffer status, available transmission power status, channelstatus, and the like of UEs, and performing scheduling is required, andthe ENBs 1 a-05 to 1 a-20 serve as such a device. One ENB typicallycontrols multiple cells. For example, in order to realize a data rate of100 Mbps, the LTE system uses, as radio access technology, orthogonalfrequency division multiplexing (hereinafter referred to as “OFDM”) in abandwidth of, for example, 20 MHz. In addition, an adaptive modulationand coding (hereinafter referred to as “AMC”) scheme is applied todetermine a modulation scheme and a channel coding rate in accordancewith the channel status of a terminal. The S-GW 1 a-30 is a device forproviding data bearers and generates or removes data bearers under thecontrol of the MME 1 a-25. The MME is a device that performs variouscontrol functions, as well as a mobility management function for aterminal, and is connected to a plurality of base stations.

FIG. 1B is a diagram illustrating a radio protocol structure in an LTEsystem to which the disclosure is applied.

Referring to FIG. 1B, the radio protocol of the LTE system includes apacket data convergence protocol (PDCP) 1 b-05 or 1 b-40, a radio linkcontrol (RLC) 1 b-10 or 1 b-35, and a medium access control (MAC) 1 b-15or 1 b-30 in a terminal and an ENB, respectively. The packet dataconvergence protocol (PDCP) 1 b-05 or 1 b-40 performs operations, suchas IP header compression/decompression and the like, and the radio linkcontrol (hereinafter referred to as “RLC”) 1 b-10 or 1 b-35 reconfiguresa PDCP packet data unit (PDU) to an appropriate size and performs an ARQoperation and the like. The MAC 1 b-15 or 1 b-30 is connected to aplurality of RLC entities configured in a single terminal and performsoperation of multiplexing RLC PDUs into MAC PDUs and demultiplexing RLCPDUs from MAC PDUs. A physical layer 1 b-20 or 1 b-25 channel-codes andmodulates upper layer data, and converts the same into OFDM symbols tothen be transmitted through a wireless channel, or demodulates OFDMsymbols received through a wireless channel and channel-decodes the sameto then be transmitted to upper layers.

FIG. 1C is a diagram illustrating a random access process in thedisclosure.

Random access is performed when performing uplink synchronization ortransmitting data over a network. More specifically, random access maybe performed when switching from an idle mode to a connected mode,performing RRC re-establishment, performing handover, and initiatinguplink and downlink data. When the terminal 1 c-05 receives a dedicatedpreamble from the base station 1 c-10, the terminal 1 c-05 may transmitthe preamble by applying the same. Otherwise, the terminal may selectone of two preamble groups, and may select a preamble belonging to theselected group. The groups will be referred to as “group A” and “groupB”. If the channel quality state is higher than a specific threshold,and if the size of msg 3 is greater than a specific threshold, apreamble belonging to group B may be selected, otherwise, a preamblebelonging to group A may be selected. If the preamble is transmitted inthe n^(th) subframe (1 c-15), a random access response (RAR) windowstarts from the (n+3)^(th) subframe, and it may be monitored whether ornot the RAR is transmitted within the window time interval (1 c-20).Scheduling information of the RAR is indicated by an RA-RNTI of a PDCCH.The RA-RNTI may be derived using the position of a radio resource intime and frequency axes, which is used to transmit the preamble. The RARincludes a timing advance command, a UL grant, and a temporary C-RNTI.If the RAR is successfully received within the RAR window, msg3 may betransmitted using information about the UL grant included in the RAR (1c-25). Msg3 includes different information depending on the purpose ofthe random access. The table below is an example of informationcontained in msg 3.

TABLE 1 Examples of information included in msg3 CASE Message 3 ContentsRRC CONNECTION SETUP CCCH SDU RRC RE-ESTABLISHMENT CCCH SDU, BSR (ifgrant is enough), PHR (if triggered & grant is enough) Handover (randompreamble) C-RNTI CE, BSR, PHR, (part of) DCCH SDU Handover (dedicatepreamble) BSR, PHR, (part of) DCCH SDU UL resume C-RNTI CE, BSR, PHR,(part of) DCCH/DTCH SDU PDCCH order (random preamble) C-RNTI CE, BSR,PHR, (part of) DCCH/DTCH SDU PDCCH order (dedicate preamble) BSR, PHR,(part of) DCCH/DTCH SDU

If the RAR is received in the n^(th) subframe, msg3 is transmitted inthe (n+⁶)^(th) subframe. HARQ is applied to Msg3. After transmittingmsg3, the terminal may drive a specific timer, and may monitor acontention resolution (CR) message until the timer expires (1 c-30). TheCR message includes an RRC connection setup, an RRC connectionre-establishment message, or the like depending on the purpose of randomaccess in addition to a CR MAC CE.

The disclosure proposes a technology in order for the terminal an idlemode (RRC_Idle) or an inactive mode (RRC_Inactive) to transmit andreceive predetermined small-sized user data during the random accessprocess to the base station without switching to a connected mode(RRC_Connected) in a mobile communication system. In the disclosure, thetechnology will be referred to as “early data transmission (EDT)”. Inparticular, the disclosure proposes a method in which the base stationtransmits user data to the terminal (mobile terminated-initiated,MT-initiated) using the EDT technology. In the disclosure, the downlinktransmission will be referred to as “downlink early data transmission(DL EDT)”. DL EDT may have various options depending on whether the userdata is transmitted while being contained in a paging message, an RAR,or msg4, and in the disclosure, and the user data is contained in theRAR and is then transmitted. Although details of the disclosure aredescribed based on an LTE system, the technology of the disclosure mayalso be applied to an NR system. For example, eNB corresponds to gNB,and MME corresponds to AMF.

FIG. 1D is a flowchart illustrating a process of including user data ina random access response message and transmitting the same in thedisclosure.

Wireless devices used in machine-type communication (MTC) or IoT(Internet of Things) need to transmit and receive very small sized userdata. For example, several-bit data is required to be transmitted andreceived in order to turn on or off some of the functions of thewireless devices. Although the random access response message (RAR) isvery limited in size, there is no big problem in transmittingseveral-bit data, and the use of RAR makes it possible to reduce thetime required to transmit and receive user data.

The terminal 1 d-05 may identify whether or not the base stationsupports EDT through system information broadcast by the base station 1d-10 (1 d-20). The base station may specifically configure whether ornot to support DL EDT or to support DL EDT using an RAR in the systeminformation. In addition, the base station may provide dedicatedpreambles used for the DL EDT operation using an RAR through the systeminformation.

The terminal may switch to a connected mode through a process ofconnection with the base station (1 d-25). The base station may make arequest to the terminal for UE capability information using apredetermined RRC message (1 d-30). The terminal may report its owncapability information to the base station (1 d-35). The UE capabilityinformation may include an indicator indicating whether or not theterminal supports DL EDT using an RAR. The base station, having obtainedthe capability information from the terminal, may transmit theinformation to the MME (1 d-40).

Paging may be triggered in the MME in order to transmit, to theterminal, small-sized user data capable of being contained in the RAR (1d-45). The MME may determine whether or not the terminal supports DL EDTusing a paging message and whether or not the user data is able to becontained in the RAR. The amount of user data capable of being containedin the RAR may be pre-reported from the base station, or may be definedas a fixed value. If the above two criteria are satisfied, the MME maytransmit small-sized user data while transmitting a paging to the basestation (1 d-50). In addition, the user data may be indicated to betransmitted through the RAR.

The base station, having received the paging and the user data, maytransmit, to the terminal, a PDCCH to which a separate RNTI indicatingthat a paging message is configured as only the paging record of a userrelated to DL EDT is applied (1 d-55). Alternatively, the PDCCH to whichan existing P-RNTI is applied may be transmitted to the terminal. Thebase station may transmit a paging message containing predeterminedinformation to the terminal (1 d-60). The paging record of the terminalthat is to receive the user data contained in the RAR may contain anindicator indicating the same and dedicated preamble information. One ormore paging records may be associated with the RAR-based DL EDT. Sincethe terminal that is to receive the user data contained in the RARdecodes all the received paging messages, the terminal may recognizewhether or not another terminal is to receive the user data through theRAR.

The terminal to receive the user data contained in the RAR may transmitthe provided dedicated preamble to the base station (1 d-65).

The base station may transmit an RAR containing an MAC RAR correspondingto the dedicated preamble (1 d-70). In general, one RAR may provide MACRARs to a plurality of terminals. The user data for a plurality ofterminals may also be contained in one RAR, and user data of eachterminal is contained in a NAS container of a corresponding MAC SDU.Therefore, there may be a plurality of NAS containers containing theuser data in one RAR. The reason for using the NAS container is to applyNAS security. DCI corresponding to the RA-RNTI transmitted in the PDCCHmay include information on the MAC SDU including the NAS container inthe RAR. For example, information on the number of MAC SDUs or NAScontainers contained in the RAR (this is the same as the number ofsubheaders related to the RAR-based DL EDT) may be included in the DCI.The above information is used for identifying the location of the MACSDU in the RAR. Alternatively, one RAR may be limited to having only oneMAC SDU.

If there is uplink user data to be transmitted in response to downlinkuser data contained in the RAR, or if the purpose of ACK/NACK is needed(1 d-75), the terminal may transmit the uplink user data or apredetermined message for the purpose of ACK/NACK using an msg3 message(1 d-80). The msg3 may be transmitted using UL grant informationprovided by the RAR.

The base station may forward the received uplink user data or ACK/NACKinformation to the MME (1 d-85).

FIG. 1E is a diagram illustrating the configuration of a random accessresponse message that does not contain user data in the disclosure.

FIG. 1EA is an example of the configuration of an RAR. One RAR includesone MAC header and one or more MAC RARs. A padding may be added as anoption. The MAC header has a variable size, and includes one or more MACPDU subheaders. Each MAC PDU subheader (i.e., an E/T/RAPID MACAsubheader) except a BI subheader (i.e., an E/T/R/R/BI subheader)corresponds to one MAC RAR. The BI subheader is included in the RAR asan option, and is located at the head of the MAC header.

FIG. 1EB is a diagram illustrating the configuration of an E/T/RAPID MACsubheader. Field E indicates whether or not another subheader existsafter the subheader. If the value is 1, another subheader existssubsequent thereto, but if the value is 0, a MAC RAR or a paddingfollows the same. Field T may indicate whether the subheader is anE/T/RAPID MAC subheader or an E/T/R/R/BI MAC subheader. If the value is0, the subheader is an E/T/R/R/BI MAC subheader, and if the value is 1,the subheader is an E/T/RAPID MAC subheader. Field RAPID is an ID of arandom access preamble, and is used to indicate the preamble that wastransmitted.

FIG. 1EC is a diagram illustrating the configuration of an E/T/R/R/BIMAC subheader. R is a reserved bit. BI indicates a backoff value. Thisinformation is used to derive a waiting time until retrying if therandom access is not successfully completed.

FIG. 1ED is a diagram illustrating the configuration of a MAC RAR.Timing advance command information indicates information on transmissiontiming to be adjusted for uplink synchronization. UL grant is schedulinginformation of msg3. A temporary C-RNTI may be used to indicate DCIcorresponding to msg4 in a PDCCH, and may be converted to a C-RNTI afterthe random access.

FIGS. 1FA and 1FB are diagrams illustrating the configuration of arandom access response message containing user data in the disclosure.

In FIG. 1FAA illustrating a first embodiment of the configuration of arandom access response message containing user data, a subheader 1 f-05including RAPID indicating a preamble related to the RAR-based DL EDTcorresponds to one MAC RAR 1 f-10 and one MAC SDU 1 f-15. The subheaderis always located after other subheaders that are not related to theRAR-based DL EDT in the MAC header. The MAC RAR and MAC SDU mapped tothe subheader are adjacent to each other, and are always located afterMAC RARs mapped to other subheaders that are not related to theRAR-based DL EDT. However, the MAC RAR and MAC SDU precede the padding.The reason for placing the MAC SDU at the rear in the MAC payload is tominimize the effect on terminals that do not support DL EDT. One RAR mayhave multiple combinations of a subheader, including RAPID indicating apreamble related to the RAR-based DL EDT, and one MAC RAR and one MACSDU, which correspond thereto. The MAC SDU has a NAS container includinguser data. There may be a predetermined RRC message containing the NAScontainer. The RRC message belongs to SRB0. The RRC message includesS-TMSI information of a terminal receiving the user data andestablishment cause information, as well as the NAS container. The causeinformation is used to indicate the type of user data. For example, thecause information may indicate MT data or delay tolerant access.

In FIG. 1FAB illustrating a second embodiment of the configuration of arandom access response message containing user data, a subheader 1 f-20including RAPID indicating a preamble related to the RAR-based DL EDTcorresponds to one MAC RAR 1 f-25 and one MAC SDU 1 f-30. The subheaderis located after a BI subheader in a MAC header, and is not limited to aspecific sequence with respect to other E/T/RAPID MAC subheaders. TheMAC RAR and MAC SDU, which are mapped to the subheader, do not need tobe adjacent to each other. The position of the mapped MAC RAR in the MACpayload is the same as the position of the subheader in the MAC header.However, the mapped MAC SDU always follows other MAC RARs. In the caseof a plurality of MAC SDUs, the sequence thereof follows the sequence ofthe mapped subheaders in the MAC header. However, they precede thepadding. The reason for placing the MAC SDU at the rear in the MACpayload is to minimize the effect on terminals that do not support DLEDT. One RAR may have multiple combinations of a subheader, includingRAPID indicating a preamble related to the RAR-based DL EDT, and one MACRAR and one MAC SDU, which correspond thereto. The MAC SDU has beendescribed in detail above.

In FIG. 1FBC illustrating a third embodiment of the configuration of arandom access response message containing user data, a subheader 1 f-35including RAPID indicating a preamble related to the RAR-based DL EDTcorresponds to one MAC RAR 1 f-40 and one MAC SDU 1 f-45. The subheaderis located after a BI subheader in a MAC header, and is not limited to aspecific sequence with respect to other E/T/RAPID MAC subheaders. TheMAC RAR and MAC SDU, which are mapped to the subheader, are adjacent toeach other. The position of the mapped MAC RAR and MAC SDU in the MACpayload is the same as the position of the subheader in the MAC header.However, the MAC RAR and MAC SDU precede the padding. One RAR may havemultiple combinations of a subheader, including RAPID indicating apreamble related to the RAR-based DL EDT, and one MAC RAR and one MACSDU, which correspond thereto. The MAC SDU has been described in detailabove.

In FIG. 1FBD illustrating a fourth embodiment of the configuration of arandom access response message containing user data, there are twosubheaders 1 f-50 and 1 f-55 including the same RAPID indicating apreamble related to the RAR-based DL EDT, and the first subheaderthereof corresponds to one MAC RAR 1 f-60, and the second subheaderthereof corresponds to one MAC SDU 1 f-65. In the MAC header, the firstsubheader always precedes the second subheader, and the first subheaderand the second subheader do not need to be adjacent to each other. Thetwo subheaders follow a BI subheader in a MAC header, and are notlimited to a specific sequence with respect to other E/T/RAPID MACsubheaders. The MAC RAR and MAC SDU, which are mapped to the subheader,do not need to be adjacent to each other. The positions of the mappedMAC RAR and MAC SDU in the MAC payload are the same as the positions ofthe corresponding subheaders in the MAC header. However, the MAC RAR andMAC SDU precede the padding. The reason for defining two subheadershaving the same RAPID is to minimize the effect on terminals that do notsupport DL EDT. One RAR may have multiple combinations of a subheader,including RAPID indicating a preamble related to the RAR-based DL EDT,and one MAC RAR and one MAC SDU, which correspond thereto. The MAC SDUhas been described in detail above.

FIG. 1G is a flowchart illustrating the operation of a terminal in thedisclosure.

In step 1 g-05, the terminal may receive a paging message from the basestation. The paging has a paging record corresponding to the terminal.In addition, an indicator indicating performing the RAR-based DL EDT anddedicated preamble information may be provided through the paging.

In step 1 g-10, the terminal may transmit the dedicated preamble to thebase station.

In step 1 g-15, the terminal may receive an RAR from the base station.

In step 1 g-20, the terminal may decode user data from a NAS containerincluded in the received RAR.

In step 1 g-25, the terminal may transmit msg3 using a UL grant providedfrom the RAR for the purpose of ACK/NACK. If there is user data requiredto be transmitted in the uplink, the msg3 may also include the data. Thedata may be contained in a NAS container, and a predetermined RRCmessage including the NAS container may be defined.

FIG. 1H is a flowchart illustrating the operation of a base station inthe disclosure.

In step 1 h-05, the base station may receive a paging for a specificterminal along with user data from the MME. At this time, the MME mayinstruct to transmit the user data to the terminal by applying RAR-basedDL EDT.

In step 1 h-10, the base station may transmit, to the terminal, a pagingincluding an indicator indicating performing of the RAR-based DL EDT andinformation on a dedicated preamble allocated for the RAR-based DL EDT.

In step 1 h-15, the base station may receive one preamble from theterminal.

In step 1 h-20, the base station may determine whether or not thepreamble is the dedicated preamble that was provided.

In step 1 h-25, if the preamble is the dedicated preamble allocated forthe DL EDT, the base station may include a corresponding MAC RAR and aMAC SDU including a NAS container, which contains user data, in an RAR.

In step 1 h-30, if the preamble is not the dedicated preamble allocatedfor the DL EDT, the base station may include a corresponding MAC RAR inthe RAR.

In step 1 h-35, the base station may transmit the configured RAR to theterminal.

In step 1 h-40, the base station may receive msg3 from the terminal. Themsg3 may include a NAS container containing the user data.

FIG. 1I is a flowchart illustrating the operation of an MME in thedisclosure.

In step 1 i-05, the MME may receive capability information for aspecific terminal from the base station. The capability information mayinclude information on whether or not the terminal supports theRAR-based DL EDT.

In step 1 i-10, the MME may trigger paging for the terminal, and mayhave user data to be transmitted through DL EDT.

In step 1 i-15, if the base station supports RAR-based DL EDT, the MMEmay transmit the paging to the base station together with the user data.

In step 1 i-20, the MME may receive, from the base station, ACKinformation indicating that the user data has been successfullytransmitted.

FIG. 1J illustrates the structure of a terminal.

Referring to the drawing, a terminal includes a radio frequency (RF)processor 1 j-10, a baseband processor 1 j-20, a storage 1 j-30, and acontroller 1 j-40.

The RF processor 1 j-10 performs a function of transmitting andreceiving a signal through a radio channel, such as band conversion andamplification of a signal. That is, the RF processor 1 j-10 up-convertsa baseband signal provided from the baseband processor 1 j-20 to an RFband signal to thus transmit the same through an antenna, anddown-converts an RF band signal received through the antenna to abaseband signal. For example, the RF processor 1 j-10 may include atransmission filter, a reception filter, an amplifier, a mixer, anoscillator, a digital-to-analog converter (DAC), an analog-to-digitalconverter (ADC), and the like. Although only one antenna is illustratedin FIG. 1J, the terminal may have a plurality of antennas. In addition,the RF processor 1 j-10 may include a plurality of RF chains. Further,the RF processor 1 j-10 may perform beamforming. To perform beamforming,the RF processor 1 j-10 may adjust the phases and magnitudes of signalstransmitted and received through a plurality of antennas or antennaelements. In addition, the RF processor may perform MIMO, and mayreceive a plurality of layers when performing MIMO.

The baseband processor 1 j-20 performs a function of conversion betweena baseband signal and a bit string according to the physical layerspecification of the system. For example, when transmitting data, thebaseband processor 1 j-20 encodes and modulates transmission bitstrings, thereby generating complex symbols. In addition, upon receivingdata, the baseband processor 1 j-20 demodulates and decodes a basebandsignal provided from the RF processor 1 j-10 to thus recover receptionbit strings. For example, in the case where an orthogonal frequencydivision multiplexing (OFDM) scheme is applied, when transmitting data,the baseband processor 1 j-20 generates complex symbols by encoding andmodulating transmission bit strings, maps the complex symbols tosubcarriers, and then configures OFDM symbols through an inverse fastFourier transform (IFFT) operation and cyclic prefix (CP) insertion. Inaddition, when receiving data, the baseband processor 1 j-20 divides thebaseband signal provided from the RF processor 1 j-10 into OFDM symbolunits, restores the signals mapped to the subcarriers through a fastFourier transform (FFT) operation, and then restores reception bitstrings through demodulation and decoding.

The baseband processor 1 j-20 and the RF processor 1 j-10 transmit andreceive signals as described above. Accordingly, the baseband processor1 j-20 and the RF processor 1 j-10 may be referred to as a“transmitter”, a “receiver”, a “transceiver”, or a “communication unit”.Further, at least one of the baseband processor 1 j-20 and the RFprocessor 1 j-10 may include a plurality of communication modules tosupport a plurality of different radio access techniques. In addition,at least one of the baseband processor 1 j-20 and the RF processor 1j-10 may include different communication modules to process signals ofdifferent frequency bands. For example, the different radio accesstechniques may include a wireless LAN (e.g., IEEE 802.11), a cellularnetwork (e.g., LTE), and the like. The different frequency bands mayinclude super-high frequency (SHF) (e.g., 2.NRHz or NRhz) bands andmillimeter wave (e.g., 60 GHz) bands.

The storage 1 j-30 stores data such as basic programs, applicationprograms, configuration information, and the like for the operation ofthe terminal. In particular, the storage 1 j-30 may store informationrelated to a second access node for performing wireless communicationusing a second radio access technique. In addition, the storage 1 j-30provides the stored data in response to a request from the controller 1j-40.

The controller 1 j-40 controls the overall operation of the terminal.For example, the controller 1 j-40 transmits and receives signalsthrough the baseband processor 1 j-20 and the RF processor 1 j-10. Inaddition, the controller 1 j-40 records and reads data in and from thestorage 1 j-40. To this end, the controller 1 j-40 may include at leastone processor. For example, the controller 1 j-40 may include acommunication processor (CP) for controlling communication and anapplication processor (AP) for controlling upper layers such asapplication programs and the like.

FIG. 1K is a block diagram illustrating the configuration of a primarybase station in a wireless communication system according to anembodiment of the disclosure.

As shown in the drawing, the base station includes an RF processor 1k-10, a baseband processor 1 k-20, a backhaul communication unit 1 k-30,a storage 1 k-40, and a controller 1 k-50.

The RF processor 1 k-10 performs a function of transmitting andreceiving signals through a radio channel, such as band conversion andamplification of a signal and the like. That is, the RF processor 1 k-10up-converts a baseband signal provided from the baseband processor 1k-20 to an RF band signal, to thus transmit the same through an antenna,and down-converts an RF band signal received through the antenna to abaseband signal. For example, the RF processor 1 k-10 may include atransmission filter, a reception filter, an amplifier, a mixer, anoscillator, a DAC, an ADC, and the like. Although only one antenna isshown in the drawing, the first access node may have a plurality ofantennas. In addition, the RF processor 1 k-10 may include a pluralityof RF chains. Further, the RF processor 1 k-10 may perform beamforming.To perform beamforming, the RF processor 1 k-10 may adjust the phasesand magnitudes of signals transmitted and received through a pluralityof antennas or antenna elements. The RF processor may perform a downlinkMIMO operation by transmitting one or more layers.

The baseband processor 1 k-20 performs a function of conversion betweena baseband signal and a bit string according to a physical layerspecification of a first radio access technique. For example, whentransmitting data, the baseband processor 1 k-20 encodes and modulatestransmission bit strings, thereby generating complex symbols. Inaddition, upon receiving data, the baseband processor 1 k-20 demodulatesand decodes a baseband signal provided from the RF processor 1 k-10 tothus recover reception bit strings. For example, in the case where anOFDM scheme is applied, when transmitting data, the baseband processor 1k-20 generates complex symbols by encoding and modulating transmissionbit strings, maps the complex symbols to subcarriers, and thenconfigures OFDM symbols through the IFFT operation and CP insertion. Inaddition, when receiving data, the baseband processor 1 k-20 divides thebaseband signal provided from the RF processor 1 k-10 into OFDM symbolunits, restores the signals mapped to the subcarriers through the FFToperation, and then restores reception bit strings through demodulationand decoding. The baseband processor 1 k-20 and the RF processor 1 k-10transmit and receive signals as described above. Accordingly, thebaseband processor 1 k-20 and the RF processor 1 k-10 may be referred toas a “transmitter”, a “receiver”, a “transceiver”, a “communicationunit”, or a “radio communication unit”.

The backhaul communication unit 1 k-30 provides an interface forperforming communication with other nodes in the network. That is, thebackhaul communication unit 1 k-30 converts a bit string, transmittedfrom the primary base station to another node, such as a secondary basestation, a core network, or the like, into a physical signal, andconverts physical signals received from other nodes into bit strings.

The storage 1 k-40 stores data such as basic programs, applicationprograms, configuration information, and the like for the operation ofthe primary base station. In particular, the storage 1 k-40 may storeinformation about bearers allocated to a connected terminal, ameasurement result reported from a connected terminal, and the like. Inaddition, the storage 1 k-40 may store information that is a criterionfor determining whether multiple connections are provided to theterminal or are released. In addition, the storage 1 k-40 provides thestored data in response to a request from the controller 1 k-50.

The controller 1 k-50 controls the overall operation of the primary basestation. For example, the controller 1 k-50 transmits and receivessignals through the baseband processor 1 k-20 and the RF processor 1k-10 or the backhaul communication unit 1 k-30. In addition, thecontroller 1 k-50 records and reads data in and from the storage 1 k-40.To this end, the controller 1 k-50 may include at least one processor.

FIG. 1L is a diagram illustrating the configuration of a random accessresponse message containing an RAR subheader having field L and an RARhaving a size L in the disclosure.

A subheader 1 l-05 including RAPID indicating a preamble related toRAR-based DL EDT may correspond to one MAC RAR 1 l-10. The subheader ischaracterized by including a predetermined field indicating the lengthof a MAC RAR corresponding thereto. The preamble indicated by RAPIDcontained in the subheader may be used only for the purpose of DL EDT,and the preamble information may be broadcast using system information.The subheader including RAPID for the DL EDT may always include field Lindicating the length of the MAC RAR corresponding thereto. That is, theterminal may determine whether or not there is a field L in thesubheader depending on whether or not RAPID is used for DL EDT. Thecorresponding MAC RAR is characterized by having a variable size. Thecontained sequence of the MAC RAR mapped to the subheader in the MACpayload of the RAR MAC PDU is the same as the contained sequence of thecorresponding subheader in the MAC header of the RAR MAC PDU. The MACRAR mapped to the subheader may precede at least the padding. One RARmay have multiple combinations of a subheader, including RAPIDindicating a preamble related to the RAR-based DL EDT, and one MAC RARand one MAC SDU, which correspond thereto. The MAC RAR having a variablesize contains a NAS container including user data. The NAS container maycontain user data required to be transmitted to the terminal by anetwork.

FIG. 1M is a diagram illustrating the configuration of an RAR subheaderincluding field L in the disclosure.

This is a configuration diagram of E/T/RAPID/L MAC subheader. Field Emay indicate whether or not another subheader exists after thesubheader. If the value of field E is 1, another subheader may existsubsequent thereto, but if the value of field E is 0, a MAC RAR or apadding may follow the same. Field T may indicate whether the subheaderis an E/T/RAPID MAC subheader (or E/T/RAPID/L MAC subheader) or anE/T/R/R/BI MAC subheader. If the value of field T is 0, the subheader isthe E/T/R/R/BI MAC subheader, and if the value of field T is 1, thesubheader is the E/T/RAPID MAC subheader (or E/T/RAPID/L MAC subheader).Field RAPID is an ID of a random access preamble, and is used toindicate the preamble that was transmitted. RAPID may always indicate apreamble used for EDT in the E/T/RAPID/L MAC subheader. Field L 1 m-05may indicate the length of a MAC RAR corresponding to the subheader.That is, the corresponding MAC RAR has a variable size. Although thesize of field L is expressed as 1 byte in FIG. 1M, the size may begreater or less than the same.

FIG. 1N is a diagram illustrating the configuration of a MAC RARincluding a NAS container in the disclosure.

The timing advance command information indicates information ontransmission timing to be adjusted for uplink synchronization. The ULgrant is scheduling information of msg3. The temporary C-RNTI may beused to indicate DCI corresponding to msg4 in a PDCCH, and may beconverted to a C-RNTI after the random access. The NAS container iscontained in the rearmost of the MAC RAR 1 n-05. The NAS container mayhave a variable size.

In another embodiment, the MAC RAR having a NAS container of a fixedsize may be considered. At this time, field L is not required for thesubheader corresponding thereto. However, the size of a MAC RARindicated by a subheader including RAPID indicating a preamble used forEDT may be different from the size of a MAC RAR indicated by a subheaderthat does not indicate a preamble used for EDT. That is, since the MACRAR corresponding to the subheader including RAPID indicating a preambleused for EDT further contains the NAS container, the size thereof isgreater than that of an existing MAC RAR. Although the size of the NAScontainer is fixed, the size is characterized by being defined in unitsof bytes.

FIG. 1O is a flowchart illustrating the operation of a terminal in thedisclosure.

In step 1 o-05, the terminal may receive a paging message from the basestation. The paging may have a paging record corresponding to theterminal. In addition, an indicator indicating performing RAR-based DLEDT and dedicated preamble information may be provided through thepaging.

In step 1 o-10, the terminal may transmit the dedicated preamble to thebase station.

In step 1 o-15, the terminal may receive an RAR from the base station.

In step 1 o-20, the terminal may recognize RAPID corresponding to apreamble used for DL EDT from among the subheaders of the RAR.

In step 1 o-25, the terminal may determine that the subheader has fieldL.

In step 1 o-30, the terminal may decode an MAC RAR corresponding to thesubheader in consideration of the size indicated by the field L.

FIG. 1P is a flowchart illustrating the operation of a base station inthe disclosure.

The base station may transmit, to the terminal, a list of dedicatedpreambles used for DL EDT using system information.

In step 1 p-05, the base station may receive a paging for a specificterminal together with user data from the MME. At this time, the MME mayinstruct to transmit the user data to the terminal by applying RAR-basedDL EDT.

In step 1 p-10, the base station may transmit, to the terminal, a pagingincluding an indicator indicating performing RAR-based DL EDT andinformation on a dedicated preamble allocated for RAR-based DL EDT.

In step 1 p-15, the base station may receive one preamble from theterminal.

In step 1 p-20, the base station may determine whether or not thepreamble is the dedicated preamble that was provided.

In step 1 p-25, if the preamble is the dedicated preamble allocated forDL EDT, the base station may include a subheader, having RAPIDcorresponding to the preamble and field L, and a MAC RAR, including aNAS container corresponding to the subheader, in an RAR.

In step 1 p-30, if the preamble is not the dedicated preamble allocatedfor DL EDT, the base station may include a corresponding MAC RAR in theRAR.

In step 1 p-35, the base station may transmit the configured RAR to theterminal.

In step 1 p-40, the base station may receive msg3 from the terminal. Themsg3 may include a NAS container containing the user data.

Second Embodiment

Hereinafter, the operational principle of the disclosure will bedescribed in detail with reference to the accompanying drawings. Indescribing the disclosure below, a detailed description of knownfunctions and configurations incorporated herein will be omitted if thedescription unnecessarily obscures the subject matter of the disclosure.In addition, the terms used herein are defined in consideration of thefunctions of the disclosure, and may be changed according to theintention or practices of the user or the operator, or the like.Therefore, the definition thereof should be based on the descriptionthroughout this specification.

In describing the disclosure below, a detailed description of knownfunctions and configurations incorporated herein will be omitted if thedescription unnecessarily obscures the subject matter of the disclosure.Hereinafter, embodiments of the disclosure will be described withreference to the accompanying drawings.

Hereinafter, terms for identifying connection nodes, terms referring tonetwork entities, terms referring to messages, terms referring tointerfaces between network entities, terms referring to a variety ofidentification information, and the like will be used only as examplesfor the convenience of explanation. Therefore, the disclosure is notlimited to the terms used herein, and other terms referring to objectshaving equivalent technical meanings may be used.

For the convenience of explanation, in the disclosure, terms and namesdefined in the 3rd generation partnership project long-term evolution(3GPP LTE) standard will be used. However, the disclosure is not limitedto the above-mentioned terms and names, and the disclosure may beequally applied to systems conforming to other standards. In thedisclosure, eNB may be used interchangeably with gNB for convenience ofdescription. That is, the base station described as eNB may representgNB.

FIG. 2A is a diagram illustrating the structure of an LTE systemaccording to an embodiment of the disclosure.

Referring to FIG. 2A, a radio access network of an LTE system includesEvolved Node Bs (hereinafter referred to as “ENBs”, “Node Bs”, or “basestations”) 2 a-05, 2 a-10, 2 a-15, and 2 a-20, a mobility managemententity (MME) 2 a-25, and a serving-gateway (S-GW) 2 a-30. User equipment(hereinafter referred to as “UE” or “terminal”) 2 a-35 accesses anexternal network through the ENBs 2 a-05 to 2 a-20 and the S-GW 2 a-30,as shown in the drawing.

In FIG. 2A, the ENBs 2 a-05 to 2 a-20 correspond to existing node Bs ina UMTS system. The ENB is connected to the UE 2 a-35 through a wirelesschannel and performs a more complex role than the existing node B. Inthe LTE system, since all user traffic including real-time services,such as VoIP (Voice over IP) through Internet protocol, is servedthrough a shared channel, a device for collecting status information,such as buffer status, available transmission power status, channelstatus, and the like of UEs, and performing scheduling is required, andthe ENBs 2 a-05 to 2 a-20 serve as such a device. One ENB typicallycontrols multiple cells. For example, in order to realize a data rate of100 Mbps, the LTE system uses, as radio access technology, orthogonalfrequency division multiplexing (hereinafter referred to as “OFDM”) in abandwidth of, for example, 20 MHz. In addition, an adaptive modulationand coding (hereinafter referred to as “AMC”) scheme is applied todetermine a modulation scheme and a channel coding rate in accordancewith the channel status of a terminal. The S-GW 2 a-30 is a device forproviding data bearers and generates or removes data bearers under thecontrol of the MME 2 a-25. The MME is a device that performs variouscontrol functions, as well as a mobility management function for aterminal, and is connected to a plurality of base stations.

FIG. 2B is a diagram illustrating a radio protocol structure in an LTEsystem according to an embodiment of the disclosure.

Referring to FIG. 2B, the radio protocol of the LTE system includes apacket data convergence protocol (PDCP) 2 b-05 or 2 b-40, a radio linkcontrol (RLC) 2 b-10 or 2 b-35, and a medium access control (MAC) 2 b-15or 2 b-30 in a terminal and an ENB, respectively. The packet dataconvergence protocol (PDCP) 2 b-05 or 2 b-40 performs operations, suchas IP header compression/decompression and the like. The primaryfunctions of the PDCP are summarized as follows.

-   -   Header compression and decompression (ROHC only)    -   Transfer of user data    -   In-sequence delivery of upper layer PDUs at PDCP        re-establishment procedure for RLC AM    -   Sequence reordering (for split bearers in DC (only support for        RLC AM): PDCP PDU routing for transmission and PDCP PDU        reordering for reception)    -   Duplicate detection of lower layer SDUs at PDCP re-establishment        procedure for RLC AM    -   Retransmission of PDCP SDUs at handover and, for split bearers        in DC, of PDCP PDUs at PDCP data-recovery procedure, for RLC AM    -   Ciphering and deciphering    -   Timer-based SDU discard in uplink.

The radio link control (hereinafter referred to as “RLC”) 2 b-10 or 2b-35 reconfigures a PDCP packet data unit (PDU) to an appropriate sizeand performs ARQ operation and the like. The primary functions of theRLC are summarized as follows.

-   -   Data transfer function (transfer of upper layer PDUs)    -   ARQ function (error correction through ARQ (only for AM data        transfer))    -   Concatenation, segmentation, and reassembly of RLC SDUs (only        for UM and AM data transfer)    -   Re-segmentation of RLC data PDUs (only for AM data transfer)    -   Reordering of RLC data PDUs (only for UM and AM data transfer)    -   Duplicate detection (only for UM and AM data transfer)    -   Protocol error detection (only for AM data transfer)    -   RLC SDU discard (only for UM and AM data transfer)    -   RLC re-establishment

The MAC 2 b-15 or 2 b-30 is connected to a plurality of RLC entitiespresent in a single terminal, multiplexes RLC PDUs into MAC PDUs, anddemultiplexes RLC PDUs from MAC PDUs. The primary functions of the MACare summarized as follows.

-   -   Mapping between logical channels and transport channels    -   Multiplexing/demultiplexing of MAC SDUs belonging to one or        different logical channels into/from transport blocks (TB)        delivered to/from the physical layer on transport channel s    -   Scheduling information reporting    -   HARQ function (error correction through HARQ)    -   Priority handling between logical channels of one UE    -   Priority handling between UEs by means of dynamic scheduling    -   MBMS service identification    -   Transport format selection    -   Padding

The physical layer 2 b-20 or 2 b-25 channel-codes and modulates upperlayer data, and converts the same into OFDM symbols to then betransmitted through a wireless channel, or demodulates OFDM symbolsreceived through a wireless channel and channel-decodes the same to thenbe transmitted to upper layers.

FIG. 2C is a diagram illustrating the structure of a next-generationmobile communication system according to an embodiment of thedisclosure.

Referring to FIG. 2c , a radio access network of a next-generationmobile communication system (hereinafter referred to as “NR” or “2 g”)includes a new radio node B (hereinafter referred to as “NR gNB” or an“NR base station”) 2 c-10 and a new radio core network (NR CN) 2 c-05 asshown in the drawing. New radio user equipment (hereinafter referred toas “NR UE” or a “terminal”) 2 c-15 accesses an external network throughthe NR gNB 2 c-10 and the NR CN 2 c-05.

In FIG. 2C, the NR gNB 2 c-10 corresponds to an evolved node B (eNB) ofan existing LTE system. The NR gNB is connected to the NR UE 2 c-15through a wireless channel, and may provide services superior to thoseof an existing node B. In the next-generation mobile communicationsystem, since all user traffic is served through a shared channel, adevice for collecting status information, such as buffer status,available transmission power status, and channel status of UEs and thelike, and performing scheduling is required. The NR NB 2 c-10 serves assuch a device. One NR gNB typically controls multiple cells. In order torealize super-high data rates compared to the existing LTE system, NRgNB may have a bandwidth equal to or greater than the existing maximumbandwidth, may employ, as radio access technology, orthogonal frequencydivision multiplexing (hereinafter referred to as “OFDM”), and mayfurther employ a beamforming technique in addition thereto. In addition,an adaptive modulation and coding (hereinafter referred to as “AMC”)scheme is applied to determine a modulation scheme and a channel codingrate in accordance with the channel status of a terminal. The NR CN 2c-05 performs functions such as mobility support, bearer configuration,and QoS configuration. The NR CN is a device that performs variouscontrol functions, as well as a mobility management function for aterminal, and is connected to a plurality of base stations. In addition,the next-generation mobile communication system may interwork with theexisting LTE system, and the NR CN is connected to an MME 2 c-25 througha network interface. The MME is connected to the eNB 2 c-30, which is anexisting base station.

FIG. 2D is a diagram illustrating a radio protocol structure of anext-generation mobile communication system according to an embodimentof the disclosure.

FIG. 2D is a diagram illustrating a radio protocol structure of anext-generation mobile communication system to which the disclosure maybe applied.

Referring to FIG. 2D, the radio protocol of the next-generation mobilecommunication system includes NR SDAP 2 d-01 or 2 d-45, NR PDCP 2 d-05or 2 d-40, NR RLC 2 d-10 or 2 d-35, and NR MAC 2 d-15 or 2 d-30 in aterminal and an NR base station, respectively.

The primary functions of the NR SDAP 2 d-01 or 2 d-45 may include someof the following functions.

-   -   Transfer of user plane data    -   Mapping between a QoS flow and a DRB for both DL and UL    -   Marking QoS flow ID in both DL and UL packets    -   Mapping reflective QoS flow to DRB for UL SDAP PDUs

With regard to the SDAP layer entity, the terminal may receive aconfiguration indicating whether or not to use a header of the SDAPlayer entity or whether or not to use functions of the SDAP layer entityfor each PDCP layer entity, for each bearer, or for each logical channelthrough an RRC message. In the case where the SDAP header is configured,the terminal may be instructed to update or reconfigure mappinginformation between the QoS flow and the data bearers in the uplink andthe downlink using a 1-bit NAS reflective QoS configuration indicatorand a 1-bit AS reflective QoS configuration indicator of the SDAPheader. The SDAP header may include QoS flow ID information indicatingthe QoS. The QoS information may be used as data processing priority,scheduling information, or the like in order to support effectiveservices.

The primary functions of the NR PDCP 2 d-05 or 2 d-40 may include someof the following functions.

-   -   Header compression and decompression (ROHC only)    -   Transfer of user data    -   In-sequence delivery of upper layer PDUs    -   Out-of-sequence delivery of upper layer PDUs    -   Sequence reordering (PDCP PDU reordering for reception)    -   Duplicate detection of lower layer SDUs    -   Retransmission of PDCP SDUs    -   Ciphering and deciphering    -   Timer-based SDU discard in uplink

The above reordering function of the NR PDCP entity indicates a functionof reordering PDCP PDUs received in a lower layer, based on a PDCPsequence number (SN), may include a function of transmitting data to anupper layer in the reordered order, may include a function of directlytransmitting data without consideration of sequence, may include afunction of reordering the sequence and recording lost PDCP PDUs, mayinclude a function of sending a status report of lost PDCP PDUs to thetransmitting end, and may include a function of making a request forretransmission of lost PDCP PDUs.

The primary functions of the NR RLC 2 d-10 or 2 d-35 may include some ofthe following functions.

-   -   Data transfer function (transfer of upper layer PDUs)    -   In-sequence delivery of upper layer PDUs    -   Out-of-sequence delivery of upper layer PDUs    -   ARQ function (error correction through ARQ)    -   Concatenation, segmentation, and reassembly of RLC SDUs    -   Re-segmentation of RLC data PDUs    -   Reordering of RLC data PDUs    -   Duplicate detection    -   Protocol error detection    -   RLC SDU discard    -   RLC re-establishment

The above in-sequence delivery function of the NR RLC entity indicates afunction of transferring RLC SDUs received from a lower layer to anupper layer in sequence, may include a function of, if a plurality ofRLC SDUs divided from one original RLC SDU is received, reassembling andtransmitting the same, may include a function of reordering the receivedRLC PDUs, based on an RLC sequence number (SN) or a PDCP sequence number(SN), may include a function of reordering the sequence and recordinglost RLC PDUs, may include a function of sending a status report of lostRLC PDUs to the transmitting end, may include a function of making arequest for retransmission of lost RLC PDUs, may include a function of,if there is a lost RLC SDU, transmitting only the RLC SDUs preceding thelost RLC SDU to an upper layer in sequence, may include a function of,if a predetermined timer expires even though there is a lost RLC SDU,transmitting all RLC SDUs received before the timer starts to an upperlayer in sequence, or may include a function of, if a predeterminedtimer expires even though there is a lost RLC SDU, transmitting all RLCSDUs received until the present to an upper layer in sequence. Inaddition, the RLC PDUs may be processed in the order of reception (inthe order of arrival, regardless of a serial number or a sequence numberthereof), and may be transmitted to the PDCP entity in a manner ofout-of-sequence delivery. In the case of segments, the segments, whichare stored in the buffer or will be received later, may be received tothen be reconfigured into one complete RLC PDU, and the RLC PDU may beprocessed, and may be transmitted to the PDCP entity. The NR RLC layermay not include a concatenation function, which may be performed in theNR MAC layer, or may be replaced with a multiplexing function of the NRMAC layer.

The out-of-sequence delivery of the NR RLC entity indicates a functionof directly delivering RLC SDUs received from a lower layer to an upperlayer, regardless of sequence thereof, may include a function of, if aplurality of RLC SDUs divided from one original RLC SDU is received,reassembling and delivering the same, and may include a function ofstoring and ordering RLC SNs or PDCP SNs of the received RLC PDUs,thereby recording the lost RLC PDUs.

The NR MAC 2 d-15 or 2 d-30 may be connected to a plurality of NR RLClayer entities present in a single terminal, and the primary functionsof the NR MAC may include some of the following functions.

-   -   Mapping between logical channels and transport channels    -   Multiplexing/demultiplexing of MAC SDUs    -   Scheduling information reporting    -   HARQ function (error correction through HARQ)\    -   Priority handling between logical channels of one UE    -   Priority handling between UEs by means of dynamic scheduling    -   MBMS service identification    -   Transport format selection    -   Padding

The NR PHY layer 2 d-20 or 2 d-25 may perform operations ofchannel-coding and modulating the upper layer data into OFDM symbols andtransmitting the same through a wireless channel, or operations ofdemodulating and channel-decoding the OFDM symbols received through thewireless channel and transmitting the same through the upper layer.

FIG. 2E is a diagram illustrating a procedure in which a base stationreleases a connection of a terminal so that the terminal switches froman RRC connected mode to an RRC idle mode and a procedure in which aterminal establishes a connection with a base station to then switchfrom an RRC idle mode to an RRC connected mode according to anembodiment of the disclosure.

According to an embodiment of the disclosure, if there is notransmission and reception of data to and from a terminal, whichtransmits and receives data in an RRC connected mode, for a certainreason or for a predetermined period of time, the base station maytransmit an RRC connection release message (RRCRelease message) to theterminal, thereby switching the terminal to an RRC idle mode (2 e-01).Afterwards, if the terminal that is currently disconnected (hereinafter“idle mode UE”) has data required to be transmitted, the terminal mayperform an RRC connection establishment process with the base station.The terminal may establish reverse transmission synchronization with thebase station through a random access process, and may transmit an RRCconnection request message (RRCSetupRequest message) to the base station(2 e-05). The RRC connection request message may include an identifierof the terminal, a reason for establishing a connection(establishmentCause), and the like. The base station may transmit an RRCconnection configuration message (RRC Setup message) such that theterminal establishes an RRC connection (2 e-10). The RRC connectionconfiguration message may include RRC connection configurationinformation and the like. The RRC connection is also called a “signalingradio bearer (SRB)”, and is used in transmission and reception of an RRCmessage, which is a control messages between the terminal and the basestation. The terminal having configured the RRC connection may transmitan RRC connection configuration complete message (RRCSetupCompletemessage) to the base station (2 e-15). The message may include a servicerequest message in which the terminal requests an AMF to configure abearer for a predetermined service. The base station may transmit aninitial terminal message containing the service request messagecontained in the RRC connection configuration complete message to theAMF (2 e-20). The AMF may determine whether or not to provide theservice requested by the terminal. If it is determined to provide theservice requested by the terminal as a result of the determination, theAMF may transmit an initial UE context setup request message to the basestation (2 e-25). The initial UE context setup request message mayinclude QoS (Quality of Service) information to be applied whenconfiguring a data radio bearer (DRB), security-related information tobe applied to the DRB (e.g., a security key, a security algorithm,etc.), and the like. The base station exchanges a security mode commandmessage (SecurityModeCommand message) (2 e-30) and a security modecomplete message (SecurityModeComplete message) (2 e-35) with theterminal in order to configure security. If the security configurationis completed, the base station may transmit, to the terminal, an RRCconnection reconfiguration message (RRCReconfiguration message) (2e-40). The RRC connection reconfiguration message may includeconfiguration information of a DRB for processing the user data, and theterminal may configure a DRB by applying the information, and maytransmit an RRC connection reconfiguration complete message(RRCReconfigurationComplete message) to the base station (2 e-45). Thebase station having completed the configuration of the DRB with theterminal may transmit an initial UE context configuration requestresponse message (initial UE context setup response message) to the AMF(2 e-50). The AMF receiving the message may perform a session managementprocedure with the UPF, thereby establishing a PDU session (2 e-55). Ifthe above procedure is completed, the terminal and the base station maytransmit and receive data through the UPF (2 e-60 and 2 e-65). Asdescribed above, a general data transmission process has three stages:RRC connection configuration, security configuration, and DRBconfiguration. In addition, the base station may transmitRRCReconfiguration message to the terminal in order to refresh, add, orchange the configuration for some reasons (2 e-70).

As described above, complex signaling procedures are required in orderfor the terminal to establish the RRC connection and switch from an RRCidle mode to an RRC connected mode. Accordingly, an RRC inactive modemay be newly defined in the next-generation mobile communication system,and the terminal and the base station may store the context of theterminal in the new mode, and, if necessary, may maintain the SI bearer.Therefore, if the terminal in an RRC inactive mode attempts to reconnectto the network, the terminal is able to faster access the network withfewer signalling procedures through the RRC reconnection configurationprocedure proposed below.

FIG. 2F is a diagram illustrating a procedure in which a base stationreleases a connection of a terminal so that the terminal switches froman RRC connected mode to an RRC inactive mode and a procedure in which aterminal establishes a connection with a base station to then switchfrom an RRC inactive mode to an RRC connected mode according to anembodiment of the disclosure.

In FIG. 2F, the terminal 2 f-01 may perform network connection with thebase station 2 f-02, and may transmit and receive data. If the basestation needs to switch the terminal to an RRC inactive mode for somereason, the base station may send an RRC connection release message(RRCRelease message) including suspend configuration information(suspendConfig) to the terminal (2 f-05) so that the terminal switchesto the RRC inactive mode.

The terminal is suggested to operate as follows when receiving theRRCRelease message including suspend configuration information asdescribed above (2 f-05).

If the RRCRelease message includes suspend configuration information(suspendConfig), the terminal may apply the received suspendconfiguration information.

A. If there is no RAN-notification area information(ran-NotificationAreaInfo) in the suspend configuration information, theterminal may apply RAN-notification area information that was previouslystored. This is intended to support delta configuration to the terminalbecause the RAN-notification area information has a large size.

B. If there is RAN-notification area information in the suspendconfiguration information, the terminal may update the stored valueswith new RAN-notification area information included in the suspendconfiguration information of the RRCRelease message.

C. If there is no t380 in the suspend configuration information, theterminal may release t380 that was previously stored.

D. If there is t380 in the suspend configuration information, theterminal may store t380 included in the suspend configurationinformation of the RRCRelease message.

E. The terminal may store a full UE connection resume identity(FullI-RNTI), a segmented UE connection resume identity (ShortI-RNTI),NCC (nextHopChainingCount), and a RAN-paging cycle (ran-PagingCycle),which are included in the suspend configuration information.

F. In addition, the terminal may reset the MAC layer entity. This isintended to prevent unnecessary retransmission of data stored in theHARQ buffer when connection is resumed.

G. In addition, the RLC layer entities may be re-established for allSRBs and DRBs. This is intended to prevent unnecessary retransmission ofdata stored in the RLC buffer when connection is resumed and toinitialize variables to be used later.

H. If the RRCRelease message with the suspend configuration informationis received for any reason, instead of a response to the RRC connectionresume request message (RRCResumeRequest message), the terminal maystore a terminal context. The terminal context may include current RRCconfiguration information, current security context information, PDCPstate information including ROHC state information, SDAP configurationinformation, a terminal cell identity (C-RNTI) used in a source cell(PCell), a cell identity (CellIdentity) of a source cell, and a physicalcell identity.

I. In addition, the terminal may suspend all SRBs and DRBs except SRB0.

J. In addition, the terminal may drive a timer t380 using a periodic RANnotification area update timer value (PeriodicRNAU-TimerValue) includedin the suspend configuration information.

K. In addition, the terminal may report suspension of the RRC connectionto an upper layer.

L. In addition, the terminal may configure lower layer entities to stopintegrity protection and encryption functions.

M. In addition, the terminal may switch to an RRC inactive mode.

If the driven timer t380 expires while the terminal 2 f-10, havingswitched to the RRC inactive mode as described above, moves, or if theterminal enters a RAN-based notification area (RNA) which does notbelong to the RAN-notification area information configured after thecell reselection process, receives a paging, or has data required to betransmitted to the base station, the terminal may perform the RRCconnection resume procedure with the base station (2 f-10).

In step 2 f-10, in the case of requesting RRC connection resumption inthe upper layer or requesting RRC connection resumption in the RRC, theterminal in the RRC inactive mode is suggested to operate as followswhen performing a random access procedure and transmitting an RRCmessage to the base station (2 f-15).

1. The terminal may select RRCResumeRequest1 as a message to betransmitted to the base station when field useFullResumeID is signaledin system information (SIB1). The terminal may include resumeIdentity,as a stored full UE connection resume identity value (fulll-RNTI value),in the RRCResumeRequest1 message, thereby preparing for transmission.Otherwise, the terminal may select RRCResumeRequest as a message to betransmitted to the base station. The terminal may prepare fortransmission by including shortResumeIdentity, as a stored segmented UEconnection resume identity value (shortI-RNTI value), in theRRCResumeRequest message.

2. The terminal may configure the reason for resuming the connection(resumeCause).

3. If the PLMN is provided from the upper layer entities or the NASlayer, the terminal may configure the PLMN selected by the upper layerentities or the NAS layer from plmn-IdentityList included in SIB1 asselectedPLMN-Identity, and may include the same in the RRCResumeRequestmessage or the RRCResumeRequest1 message, thereby preparing fortransmission.

4. The terminal may calculate MAC-I, and may include the same in theselected message, thereby preparing for transmission.

5. The terminal may recover RRC configuration and security contextinformation, excluding cell group configuration information(cellGroupConfig), from the stored terminal context.

6. The terminal may update a new KgNB security key, based on the currentKgNB security key, a NextHop (NH) value, and a stored NCC value.

7. In addition, the terminal may derive new security keys (K_RRCenc,K_RRC_int, K_UPint, and K_UPenc) to be used in the integrity protectionand verification procedures, and encryption and decryption proceduresusing the newly updated KgNB security key.

8. In addition, the terminal resumes the integrity protection andverification procedures by applying the updated security keys and thepreviously configured algorithm to all bearers except SRB0, and appliesintegrity verification and protection to data transmitted and receivedthereafter. This is intended to increase reliability and security of thedata transmitted and received from and to SRB1 or DRBs thereafter.

9. In addition, the terminal resumes the encryption and decryptionprocedure by applying the updated security keys and the previouslyconfigured algorithm to all bearers except SRB0, and applies encryptionand decryption to data transmitted and received thereafter. This is toincrease reliability and security of data transmitted and received fromthe SRB1 or the DRBs thereafter.

10. The terminal may recover the PDCP state, and may re-establish PDCPentities for SRB1.

11. The terminal resumes SRB1. This is due to the fact that theRRCResume message is received through SRB1 in response to theRRCResumeRequset message or the RRCResumeRequest1 message to betransmitted.

12. The terminal may configure an RRCResumeRequset message or anRRCResumeRequest1 message, which is a message selected to be transmittedto the base station, and may transmit the same to lower layer entities.

13. The terminal may drive a timer T319 when transmitting theRRCResumeRequest message or the RRCResumeRequest1 message to the basestation.

The terminal is suggested to operate as follows when performing therandom access procedure in order to perform the RAN-based notificationarea update (RNA Update, RNAU) procedure and transmitting theRRCResumeRequest message or the RRCResumeRequest1 message to the basestation as described above, and then receiving an RRC connection resumemessage (RRCResume message) in response thereto (2 f-20).

1. The terminal may stop the timer T319 driven when transmitting theRRCResumeRequest message or the RRCResumeRequest1 message to the basestation.

2. If the RRCResume message includes full configuration information(fullConfig), the terminal performs a full configuration procedure.Otherwise, upon receiving the message, the terminal restores the PDCPstate and resets a COUNT value for SRB2 and all DRBs. In addition, theterminal restores cell group configuration information (cellGroupConfig)from the stored terminal context. Then, the terminal notifies the lowerlayer entities of the same.

3. The terminal releases the full UE connection resume identity(FullI-RNTI), the segmented UE connection resume identity (ShortI-RNTI),and the stored terminal context. At this time, the RAN-notification areainformation (ran-NotificatioAreaInfo) is not released.

4. If the RRCResume message includes master cell group (masterCellgroup)configuration information, the terminal may perform a cell groupconfiguration procedure according to configuration information.

5. If the message includes bearer configuration information(radioBearerConfig), the terminal may configure a bearer according tothe configuration information.

6. The terminal may resume SRB2 and all DRBs.

7. The terminal discards any stored cell reselection priorityinformation. The information may be cell reselection priorityinformation that is stored from CellReselectionPriorities, which may becontained in the RRCRelease message, or is given by another RAT.

8. The terminal may stop the timer T320 if it is running.

9. If the RRCResume message includes frequency measurement configurationinformation (measConfig), the terminal may measure frequency accordingto the configuration information.

10. If the RRC connection is suspended, the terminal may resume thefrequency measurement.

11. The terminal may switch to an RRC connected mode (2 f-25).

12. The terminal notifies the upper layer entities of resumption of thesuspended RRC connection.

13. The terminal may stop the cell reselection procedure.

14. The terminal regards the currently connected cell as a primary cell(PCell).

15. In addition, the terminal may configure an RRC connection resumecomplete message (RRCResumeComplete message) as follow, and may transmitthe same to the lower layer entities (2 f-30).

A. If the upper layer entities provide a NAS PDU, the NAS PDU may beincluded in a dedicatedNAS-Message.

B. If a PLMN is provided from the upper layer entities or the NAS layer,the PLMN selected by the upper layer entities or the NAS layer fromplmn-IdentityList included in SIB1 may be configured asselectedPLMN-Identity.

FIG. 2G is a diagram illustrating a process of reselecting a cell when aterminal is in an RRC idle mode or an RRC inactive mode according to anembodiment of the disclosure.

A cell reselection process may indicate a procedure in which a terminalin an RRC idle mode or an RRC inactive mode determines whether tomaintain the current serving cell or to reselect a neighbor cell whenthe service quality of the serving cell becomes lower than the servicequality of the neighbor cell for some reasons or due to movementthereof.

In the case of handover, whether or not to perform handover may bedetermined by the network (MME, AMF, source eNB, or source gNB), whereasin the case of cell reselection, the terminal may determine whether ornot to perform cell reselection by itself, based on the measurementquantity of the terminal. The cell to be reselected by the movingterminal may be a cell using the same NR frequency as the serving cellon which the terminal currently camps (intra-frequency), a cell using adifferent NR frequency therefrom (inter-frequency), or a cell usingother radio access technologies (inter-RAT).

The terminal in the RRC idle mode or the RRC inactive mode (2 g-01) mayperform a series of operations while camping on the serving cell (2g-05).

In step 2 g-10, the terminal in the RRC idle mode or the RRC inactivemode may receive system information broadcast by the base station of theserving cell. At this time, the terminal in the RRC idle mode or the RRCinactive mode may not receive system information broadcast by the basestation in the neighbor cell. The system information may be divided intoa master information block (MIB) and system information blocks (SIBs).Additionally, the system information blocks may be divided into andreferred to as “SIB1” and “SI messages” (e.g., SIB2, SIB3, SIB4 or SIB5)excluding SIB1. The terminal in the RRC idle mode or the RRC inactivemode may receive and read system information (e.g., MIB, or SIB1 orSIB2) broadcast by the base station of the serving cell before campingthereon. For reference, MIB and SIB1 may be system information that iscommonly applied to all terminals. SIB2 may be system information thatis commonly applied when the terminal in the RRC idle mode or the RRCinactive mode reselects the intra-frequency, inter-frequency, orinter-RAT cell. SIB3, SIB4, and SIB5 may include information necessaryin order for the terminal in the RRC idle mode or the RRC inactive modeto reselect a cell.

The system information block (SIB) 1 may include parameters such as aminimum reception level, minimum signal quality, a threshold, and thelike, which are used when determining whether or not to measure thesignal of the serving cell, and this may be cell-specific informationapplied to each cell. SIB2, SIB3, SIB4, and SIB5 may include informationon parameters such as a minimum reception level, minimum signal quality,a threshold, and the like, which are used when determining whether ornot to measure the signal of the neighbor cell. Specifically, SIB2 mayinclude common information for reselection of the intra-frequency,inter-frequency, or inter-RAT cell, SIB3 may include information onlyfor reselection of the intra-frequency cell, SIB4 may includeinformation only for reselection of the inter-frequency cell, and SIB5may include information only for reselection of the inter-RAT cell.

In step 2 g-15, the terminal in the RRC idle mode or the RRC inactivemode may be enabled in a discontinuous reception (DRX) cycle, and maymeasure the reference signal received power (RSRP) (Q_(rxlevmeas)) andthe reference signal received quality (RSRQ) (Q_(qualmeas)) of theserving cell (2 g-15). The terminal is suggested to operate as followswhen deriving the measurement quantity of the cell.

1. For cell selection in multi-beam operations, the measurement quantityof the cell may be derived by implementation of the terminal.

2. For cell reselection in multi-beam operations, the measurementquantity of the cell may be derived based on a plurality of beamscorresponding to the same cell, based on the SSB, and one of thefollowing methods may be used.

A. If nrofSS-BlocksToAverage or absThreshSS-BlocksConsolidation is notpresent in SIB2, or if the measurement quantity of the highest beam isless than or equal to the configured absThreshSS-BlocksConsolidation,the measurement quantity of the highest beam may be derived as themeasurement quantity of the cell.

B. Otherwise, the terminal may derive the measurement quantity of thecell as the linear average of the power values up to the maximumnrofSS-BlocksToAverage among the measurement quantities of the highestbeam above the configured absThreshSS-BlocksConsolidation.

The terminal may calculate the reception level (Srxlev) and thereception quality (Sqaul) of the serving cell using the parametersreceived from SIB1 through the above measurement quantity. The terminalmay compare the calculated values with thresholds, and may determinewhether or not to perform measurement of the neighbor cell for cellreselection. The reception level (Srxlev) and the reception quality(Sqaul) of the serving cell may be determined using Equation 1 below.

Srxlev=Q _(rxlevmeas)−(Q _(rxlevmin) +Q _(rxlevminoffset))−P_(compensation) −Qoffset_(temp)

Squal=Q _(qualmeas)−(Q _(qualmin) +Q_(qualminoffset))−Qoffset_(temp)  Equation 1

The parameters used in Equation 1 may be defined with reference to the3GPP standard document “38.304: User Equipment (UE) procedures in Idlemode and RRC Inactive state”. This will be the same in the embodimentsof the disclosure to which Equation 1 is applied below.

The terminal in the RRC idle mode or the RRC inactive mode may determinewhether or not to perform measurement of neighbor cells, based on ameasurement rule, instead of performing measurement of neighbor cells atall times, in order to minimize battery consumption (2 g-20). At thistime, the terminal in the RRC idle mode or the RRC inactive mode may notreceive system information broadcast by the base station of the neighborcell, and may perform measurement of neighbor cells using systeminformation broadcast by the serving cell on which the terminalcurrently camps. If the reception level (Srxlev) and the receptionquality (Squal) of the current serving cell, which are measured in step2 g-15, are less than thresholds (Srxlev<=S_(IntraSearchP) andSqual<=S_(IntraSeachQ)), the terminal in the RRC idle mode or the RRCinactive mode may measure neighbor cells using the same frequency as theserving cell (2 g-20). That is, the signal qualities (Squal) or thereception levels (Srxlev) of the neighbor cells using the same frequencyas the serving cell may be derived based on SIB2 or SIB3 broadcast fromthe serving cell (Equation 1 is applied).

For reference, information on the thresholds S_(IntraSearchP) andS_(IntrasearchQ) is included in SIB2. In addition, for theinter-frequency/inter-RAT cells having higher priority than thefrequency of the current serving cell, the measurement of neighbor cellsmay be performed regardless of the quality of the serving cell (2 g-20).That is, the signal qualities (Squal) or the reception levels (Srxlev)of the inter-frequency cells having higher priority than the frequencyof the serving cell may be derived based on SIB4 broadcast from theserving cell (Equation 1 is applied), and the signal qualities (Squal)or the reception levels (Srxlev) of the inter-RAT cells having higherpriority than the frequency of the serving cell may be derived based onSIB5 broadcast from the serving cell (Equation 1 is applied). Inaddition, for the inter-frequency cells having priority equal to orlower than the frequency of the serving cell, or for the inter-RATfrequency cells having lower priority than the frequency of the servingcell, if the reception level (Srxlev) and the reception quality (Squal)of the current serving cell, which are measured in step 2 g-15, are lessthan thresholds (Srxlex<=S_(nonIntraSearchP) andSqual<=S_(intraSearchQ)), the terminal in the RRC idle mode or in theRRC inactive mode may measure neighbor cells using different frequenciesfrom the serving cell or cells using different radio access technologiesfrom the serving cell (2 g-20). That is, the signal quality (Squal) orthe reception level (Srxlev) of the inter-frequency cell(s) havingpriority lower than or equal to the frequency of the serving cell may bederived based on SIB4 broadcast from the serving cell (Equation 1 isapplied), and the signal quality (Squal) or the reception level (Srxlev)of the inter-RAT cell(s) having lower priority than the frequency of theserving cell may be derived based on SIB5 broadcast from the servingcell (Equation 1 applied). For reference, information on the thresholdsS_(nonIntraSearchP) and S_(nonIntraSearchQ) are included in SIB2.

The terminal in the RRC idle mode or the RRC inactive mode may perform acell reselection evaluation process based on the priority(CellReselectionPriority), based on the measurement quantities (2 g-20)of the neighbor cells (2 g-25). That is, in the case where several cellssatisfying the cell reselection criteria have different priorities,reselecting the frequency/RAT cell having higher priority is prioritizedrather than reselecting the frequency/RAT cell having lower priority.Information on the priority is included in the system information (SIB1,SIB2, SIB3, SIB4, or SIB5) broadcast from the serving cell, or isincluded in the RRCRelease message received when switching from the RRCconnected mode to the RRC idle mode or the RRC inactive mode. In thereselection evaluation process of the inter-frequency/inter-RAT cellhaving higher priority than the frequency of the current serving cell,the terminal may operate as follows.

First Operation:

In the case where SIB2 including a threshold of threshServingLowQ isbroadcast and where the terminal camps on the current serving cell formore than 1 second, if the signal quality (Squal) of theinter-frequency/inter-RAT cell is greater than a thresholdThresh_(X,HighQ) during a specific time interval Treselection_(RAT)(Squal>Thresh_(X,HighQ)), the terminal may perform reselection to theinter-frequency/inter-RAT cell.

Second Operation:

If the terminal fails to perform the first operation, the terminal mayperform a second operation.

If the terminal camps on the current serving cell for more than 1second, and if the reception level (Srxlev) of theinter-frequency/inter-RAT cell is greater than a thresholdThresh_(X,HighP) during a specific time interval Treselection_(RAT)(Srxlev>Thresh_(X,HighP)), the terminal may perform reselection to theinter-frequency/inter-RAT cell.

Here, the terminal may perform the first operation or the secondoperation, based on the information included in SIB4 broadcast from theserving cell, such as the signal quality (Squal) and the reception level(Srxlev) of the inter-frequency cell, the thresholds (Threh_(X,HighQ)and Thresh_(X,HighP)), and the value Treselection_(RAT). In addition,the terminal may perform the first operation or the second operation,based on the information included in SIB5 broadcast from the servingcell, such as the signal quality (Squal) and the reception level(Srxlev) of the inter-RAT cell, the thresholds (Threh_(X,HighQ) andThresh_(X,HighP)), and the value Treselection_(RAT). For example, SIB4may include a value Q_(qualmin), a value Q_(rxlevmin), or the like, andthe signal quality (Squal) or the reception level (Srxlev) of theinter-frequency cell may be derived based on the same.

In addition, in the reselection evaluation process of theintra-frequency/inter-frequency cell having the same priority as thefrequency of the current serving cell, the terminal may operate asfollows.

Third Operation:

If the signal quality (Squal) and the reception level (Srxlev) of theintra-frequency/inter-frequency cell are greater than 0, the terminalmay derive rankings of all cells that satisfy the cell selectioncriterion S, based on the measurement quantity (RSRP). The rankings ofthe serving cell and the neighbor cells may be calculated throughEquation 2 below.

R _(s) =Q _(meas,s) −Q _(hyst)

R _(n) =Q _(meas,n) −Q _(offset)  Equation 2

A. Here, Q_(meas,s) is the measurement quantity RSRP of the servingcell, Q_(meas,n) is the measurement quantity RSRP of the neighbor cell,Q_(hyst) is the hysteresis value of the serving cell, and Q_(offset) isthe offset between the serving cell and the neighbor cell. The valueQ_(hyst) is included in SIB2, and this value may be commonly used forreselection of the intra-frequency/inter-frequency cell. In the case ofreselection of the intra-frequency cell, Q_(offset) is signaled for eachcell, is applied only to the indicated cell, and is included in SIB5. Inthe case of reselection of the inter-frequency cell, Q_(offset) issignaled for each cell, is applied only to the indicated cell, and isincluded in SIB4. In the case where rangetoBestCell is absent from SIB2broadcast from the serving cell, if the ranking of the neighbor cellobtained through Equation 2 is higher than the ranking of the servingcell (R_(−n)>Rs) during a specific time interval Treselection_(RAT), andif the terminal camps on the current serving cell for more than 1second, the terminal may camp on the highest ranked cell among theneighbor cells. In the case where rangeToBestCell is present in SIB2broadcast from the serving cell, reselection may be performed for thecell with the highest number of beams above the thresholdabsThreshSS-BlocksConsolidation, among the cells whose value R is withinrangeToBestCell of the value R of the highest ranked cell. If a new cellsatisfying the above criterion is better than the serving cell during aspecific time interval Treselection_(RAT), and if the terminal camps onthe current serving cell for more than 1 second, reselection to the newcell may be performed.

Further, in the reselection evaluation process of theinter-frequency/inter-RAT cell having lower priority than the frequencyof the current serving cell, the terminal may operate as follows.

Fourth Operation:

In the case where SIB2 including a threshold of threshServingLowQ isbroadcast and where the terminal camps on the current serving cell formore than 1 second, if the signal quality (Squal) of the current servingcell is less than a threshold Thresh_(Serving,LowQ)(Squal<Thresh_(Serving,LowQ)), and if the signal quality (Squal) of theinter-frequency/inter-RAT cell is greater than a thresholdThresh_(X,LowQ) during a specific time interval Treselection_(RAT)(Squal>Thresh_(X,LowQ)), the terminal may perform reselection to thecorresponding inter-frequency/inter-RAT cell.

Fifth Operation:

If the terminal fails to perform the fourth operation, the terminal mayperform a fifth operation.

If the terminal camps on the current serving cell for more than 1second, if the reception level (Srxlev) of the current serving cell isless than a threshold Thresh_(Serving,LowP)(Srxlev<Thresh_(Serving,LowP)), and if the reception level (Srxlev) ofthe inter-frequency/inter-RAT cell is greater than a thresholdThresh_(X,LowQ) during a specific time interval Treselection_(RAT)(Srxlev>Thresh_(X,LowP)), the terminal may perform reselection to thecorresponding inter-frequency/inter-RAT cell.

Here, the terminal may perform the fourth operation or the fifthoperation on the inter-frequency cell, based on the thresholds(Thresh_(Serving,LowQ) and Thresh_(Serving,LowP)), which are included inSIB2 broadcast from the serving cell, and the signal quality (Squal) andreception level (Srxlev) of the inter-frequency cell, the thresholds(Threh_(X,LowQ) and Thresh_(X,LowP)), and the Treselection_(RAT), whichare included in SIB4 broadcast from the serving cell. The terminal mayperform the fourth operation or the fifth operation on the inter-RATcell, based on the thresholds (Thresh_(Serving,LowQ) andThresh_(Serving,LowP)), which are included in SIB2 broadcast from theserving cell, and the signal quality (Squal) and reception level(Srxlev) of the inter-RAT cell, the thresholds (Threh_(X,LowQ) andThresh_(X,LowP)), and the Treselection_(RAT), which are included in SIB5broadcast from the serving cell. For example, SIB4 may include a valueQ_(qualmin) a value Q_(rxlevmin), or the like, and the signal quality(Squal) or the reception level (Srxlev) of the inter-frequency cell maybe derived based on the same.

In step 2 g-30, the terminal may receive system information (e.g., MIBand/or SIB1) broadcast from the cell before finally reselecting acandidate target cell, based on the priority in step 2 g-25, and maymeasure the signal of the corresponding cell in order to camp thereon (2g-30).

That is, if a candidate target cell is not indicated to be barred or isnot regarded as being barred, based on MIB and/or SIB1 broadcast fromthe corresponding cell, the terminal may derive the reception level(Srxlev) and reception quality (Squal) of the corresponding cell, basedon the received SIB1, may determine whether or not the reception level(Srxlev) and the reception quality (Squal) satisfy the cell selectioncriterion (S-criterion) (Srxlev>0 and Squal>0), and may camp on thecorresponding cell, thereby performing reselection.

FIGS. 2HA and 2HB are diagrams illustrating a process of reselecting anintra-frequency/inter-frequency cell having priority equal to thefrequency of a serving cell when a terminal is in an RRC idle mode or anRRC inactive mode according to an embodiment of the disclosure.

The terminal in the RRC idle mode or the RRC inactive mode (2 h-01) maycamp on the serving cell (2 h-05), thereby performing a series ofoperations.

In step 2 h-10, the terminal in the RRC idle mode or the RRC inactivemode may receive system information broadcast by a base station of theserving cell. At this time, the terminal in the RRC idle mode or the RRCinactive mode may not receive system information broadcast by a basestation in the neighbor cell. The system information may be divided intoa master information block (MIB) and system information blocks (SIBs).Additionally, the system information blocks may be divided into andreferred to as “SIB1” and “SI messages” (e.g., SIB2, SIB3, SIB4 or SIB5)excluding SIB1. The terminal in the RRC idle mode or the RRC inactivemode may receive and read system information (e.g., MIB, or SIB1 orSIB2) broadcast by the base station of the serving cell before campingthereon. For reference, MIB and SIB1 may be system information that iscommonly applied to all terminals. SIB2 may be system information thatis commonly applied when the terminal in the RRC idle mode or the RRCinactive mode reselects the intra-frequency, inter-frequency, orinter-RAT cell. SIB3, SIB4, and SIB5 may include information necessaryin order for the terminal in the RRC idle mode or the RRC inactive modeto reselect a cell.

SIB1 may include parameters such as a minimum reception level, minimumsignal quality, a threshold, and the like, which are used whendetermining whether or not to measure the signal of the serving cell,and this may be cell-specific information applied to each cell. SIB2,SIB3, SIB4, and SIB5 may include information on parameters such as aminimum reception level, minimum signal quality, a threshold, and thelike, which are used when determining whether or not to measure thesignal of the neighbor cell. Specifically, SIB2 may include commoninformation for reselection of the intra-frequency, inter-frequency, orinter-RAT cell, SIB3 may include information only for reselection of theintra-frequency cell, SIB4 may include information only for reselectionof the inter-frequency cell, and SIB5 may include information only forreselection of the inter-RAT cell.

In step 2 h-15, the terminal in the RRC idle mode or the RRC inactivemode may be enabled in a discontinuous reception (DRX) cycle, and maymeasure the reference signal received power (RSRP) (Q_(rxlevmeas)) andthe reference signal received quality (RSRQ) (Q_(qualmeas)) of theserving cell (2 h-15). The terminal is suggested to operate as followswhen deriving the measurement quantity of the cell.

1. For cell selection in multi-beam operations, the measurement quantityof the cell may be derived by implementation of the terminal.

2. For cell reselection in multi-beam operations, the measurementquantity of the cell may be derived based on a plurality of beamscorresponding to the same cell, based on SSB, and one of the followingmethods may be used.

A. If nrofSS-BlocksToAverage or absThreshSS-BlocksConsolidation is notpresent in SIB2, or if the measurement quantity of the highest beam isless than or equal to the configured absThreshSS-BlocksConsolidation,the measurement quantity of the highest beam may be derived as themeasurement quantity of the cell.

B. Otherwise, the terminal may derive the measurement quantity of thecell as the linear average of the power values up to the maximumnrofSS-BlocksToAverage, among the measurement quantities of the highestbeam above the configured absThreshSS-BlocksConsolidation.

The terminal may calculate the reception level (Srxlev) and thereception quality (Sqaul) of the serving cell using parameters receivedfrom SIB1 through the above measurement quantities. The terminal maycompare the calculated values with thresholds, and may determine whetheror not to perform measurement of neighbor cells for cell reselection.The reception level (Srxlev) and the reception quality (Sqaul) of theserving cell may be determined through Equation 1 described above.

The terminal in the RRC idle mode or the RRC inactive mode may determinewhether or not to perform measurement of neighbor cells, based on ameasurement rule, instead of performing measurement of neighbor cells atall times, in order to minimize battery consumption (2 h-20). At thistime, the terminal in the RRC idle mode or the RRC inactive mode may notreceive system information broadcast by the base stations of theneighbor cells, and may perform measurement of neighbor cells usingsystem information broadcast by the serving cell on which the terminalcurrently camps. If the reception level (Srxlev) and the receptionquality (Squal) of the current serving cell, which are measured in step2 h-15, are less than thresholds (Srxlev<=S_(IntraSearchP) andSqual<=S_(IntraSeachQ)), the terminal in the RRC idle mode or the RRCinactive mode may measure neighbor cells using the same frequency as theserving cell (2 h-20). That is, the signal qualities (Squal) or thereception levels (Srxlev) of the neighbor cells using the same frequencyas the serving cell may be derived based on SIB2 or SIB3 broadcast fromthe serving cell (Equation 1 is applied).

For reference, information on the thresholds S_(IntraSearchP) andS_(IntrasearchQ) is included in SIB2. In addition, for theinter-frequency/inter-RAT cells having higher priority than thefrequency of the current serving cell, the measurement of neighbor cellsmay be performed regardless of the quality of the serving cell (2 h-20).That is, the signal qualities (Squal) or the reception levels (Srxlev)of the inter-frequency cells having higher priority than the frequencyof the serving cell may be derived based on SIB4 broadcast from theserving cell (Equation 1 is applied), and the signal qualities (Squal)or the reception levels (Srxlev) of the inter-RAT cells having higherpriority than the frequency of the serving cell may be derived based onSIB5 broadcast from the serving cell (Equation 1 is applied). Inaddition, for the inter-frequency cells having priority equal to orlower than the frequency of the serving cell, or for the inter-RATfrequency cells having lower priority than the frequency of the servingcell, if the reception level (Srxlev) and the reception quality (Squal)of the current serving cell, which are measured in step 2 h-15, are lessthan thresholds (Srxlex<=S_(nonIntraSearchP) andSqual<=S_(intraSearchQ)), the terminal in the RRC idle mode or in theRRC inactive mode may measure neighbor cells using different frequenciesfrom the serving cell or cells using different radio access technologiesfrom the serving cell (2 h-20). That is, the signal quality (Squal) orthe reception level (Srxlev) of the inter-frequency cell(s) havingpriority lower than or equal to the frequency of the serving cell may bederived based on SIB4 broadcast from the serving cell (Equation 1 isapplied), and the signal quality (Squal) or the reception level (Srxlev)of the inter-RAT cell(s) having lower priority than the frequency of theserving cell may be derived based on SIB5 broadcast from the servingcell (Equation 1 applied). For reference, information on the thresholdsS_(nonIntraSearchP) and S_(nonIntraSearchQ) are included in SIB2.

The terminal in the RRC idle mode or the RRC inactive mode may perform acell reselection evaluation process, based on priority(CellReselectionPriority), based on the measurement quantities (2 h-20)of the neighbor cells (2 h-25). Information on the priority is includedin the system information (SIB1, SIB2, SIB5, SIB4, or SIB5) broadcastfrom the serving cell, or is included in the RRCRelease message receivedwhen switching from the RRC connected mode to the RRC idle mode or theRRC inactive mode.

In the reselection evaluation process of theintra-frequency/inter-frequency cell having the same priority as thefrequency of the current serving cell, the terminal may operate asfollows.

-   -   The terminal may perform ranking of all cells that satisfy the        cell selection criterion (S-criterion) (Srxlev>0 and/or Squal>0)        through Equation 1 described above (2 h-25).

A. At this time, for the cells satisfying the above criterion, theterminal may perform ranking of the current serving cell and theneighbor cells through an average RSRP, based on a cell-raking criterion(R-criterion) using Equation 2 above.

The terminal may perform a cell reselection evaluation process, based onone or more of the following methods.

-   -   In the case where rangeToBestCell is absent from SIB2 broadcast        from the serving cell, if the ranking of the neighbor cell        obtained through Equation 2 is greater than the ranking of the        serving cell during a specific time interval Treselection_(RAT)        (R_(n)>R_(s)), and if the terminal camps on the current serving        cell for more than 1 second, the terminal may reselect the        highest ranked cell from among the neighbor cells (2 h-30).    -   In the case where rangeToBestCell is present in SIB2 broadcast        from the serving cell and where nrofSS-BlocksToAverage is absent        from SIB2 and/or SIB4 broadcast from the serving cell, if the        ranking of the neighbor cell obtained through Equation 2 is        greater than the ranking of the serving cell during a specific        time interval Treselection_(RAT) (R_(n)>R_(s)), and if the        terminal camps on the current serving cell for more than 1        second, the terminal may camp on the highest ranked cell among        the neighbor cells (2 h-35).    -   In the case where rangeToBestCell is present in SIB2 broadcast        from the serving cell and where nrofSS-BlocksToAverage is        present in SIB2 and/or SIB4 broadcast from the serving cell, if        there are cells in which the number of beams above        absThreshSS-BlocksConsolidation is larger than        nrofSS-BlocksToAverage, among the cells whose value R is within        rangeToBestCell of the value R of the highest ranked cell, if        the ranking of the neighbor cell obtained through Equation 2 is        greater than the ranking of the serving cell during a specific        time interval Treselection_(RAT) (R_(n)>R_(s)), and if the        terminal camps on the current serving cell for more than 1        second, the terminal may camp on the highest ranked cell among        the neighbor cells (2 h-40).    -   If rangeToBestCell is present in SIB2 broadcast from the serving        cell, the terminal may perform reselection to the cell with the        highest ratio of the number of beams above the threshold        absThreshSS-BlocksConsolidation to the total number of beams for        each cell, among the cells whose value R is within        rangeToBestCell of the value R of the highest ranked cell. At        this time, if the new cell to be reselected is better than the        serving cell during a specific time interval Treselection_(RAT),        and if the terminal camps on the current serving cell for more        than 1 second, the terminal may perform reselection to the new        cell (2 h-45).

In step 2 h-50, the terminal may receive system information (e.g., MIBand/or SIB1) broadcast from a candidate target cell before finallyreselecting the corresponding cell, and may measure the signal of thecorresponding cell in order to camp thereon. That is, if a candidatetarget cell is not indicated to be barred or is not regarded as beingbarred, based on MIB and/or SIB1 broadcast from the corresponding cell,the terminal may derive the reception level (Srxlev) and receptionquality (Squal) of the corresponding cell, based on the received SIB1,may determine whether or not the reception level (Srxlev) and thereception quality (Squal) satisfy the cell selection criterion(S-criterion) (Srxlev>0 and Squal>0), and may camp on the correspondingcell, thereby performing reselection.

FIG. 2I is a block diagram illustrating an internal structure of aterminal according to an embodiment of the disclosure.

Referring to the drawing, a terminal includes a radio frequency (RF)processor 2 i-10, a baseband processor 2 i-20, a storage 2 i-30, and acontroller 2 i-40.

The RF processor 2 i-10 performs a function of transmitting andreceiving a signal through a radio channel, such as band conversion andamplification of a signal. That is, the RF processor 2 i-10 up-convertsa baseband signal provided from the baseband processor 2 i-20 to an RFband signal to thus transmit the same through an antenna, anddown-converts an RF band signal received through the antenna to abaseband signal. For example, the RF processor 2 i-10 may include atransmission filter, a reception filter, an amplifier, a mixer, anoscillator, a digital-to-analog converter (DAC), an analog-to-digitalconverter (ADC), and the like. Although only one antenna is illustratedin FIG. 2i , the terminal may have a plurality of antennas. In addition,the RF processor 2 i-10 may include a plurality of RF chains. Further,the RF processor 2 i-10 may perform beamforming. To perform beamforming,the RF processor 2 i-10 may adjust the phases and magnitudes of signalstransmitted and received through a plurality of antennas or antennaelements. In addition, the RF processor may perform MIMO, and mayreceive a plurality of layers when performing MIMO.

The baseband processor 2 i-20 performs a function of conversion betweena baseband signal and a bit string according to the physical layerspecification of the system. For example, when transmitting data, thebaseband processor 2 i-20 encodes and modulates transmission bitstrings, thereby generating complex symbols. In addition, upon receivingdata, the baseband processor 2 i-20 demodulates and decodes a basebandsignal provided from the RF processor 2 i-10 to thus recover receptionbit strings. For example, in the case where an orthogonal frequencydivision multiplexing (OFDM) scheme is applied, when transmitting data,the baseband processor 2 i-20 generates complex symbols by encoding andmodulating transmission bit strings, maps the complex symbols tosubcarriers, and then configures OFDM symbols through an inverse fastFourier transform (IFFT) operation and cyclic prefix (CP) insertion. Inaddition, when receiving data, the baseband processor 2 i-20 divides thebaseband signal provided from the RF processor 2 i-10 into OFDM symbolunits, restores the signals mapped to the subcarriers through a fastFourier transform (FFT) operation, and then restores reception bitstrings through demodulation and decoding.

The baseband processor 2 i-20 and the RF processor 2 i-10 transmit andreceive signals as described above. Accordingly, the baseband processor2 i-20 and the RF processor 2 i-10 may be referred to as a“transmitter”, a “receiver”, a “transceiver”, or a “communication unit”.Further, at least one of the baseband processor 2 i-20 and the RFprocessor 2 i-10 may include a plurality of communication modules tosupport a plurality of different radio access techniques. In addition,at least one of the baseband processor 2 i-20 and the RF processor 2i-10 may include different communication modules to process signals ofdifferent frequency bands. For example, the different radio accesstechniques may include a wireless LAN (e.g., IEEE 802.11), a cellularnetwork (e.g., LTE), and the like. The different frequency bands mayinclude super-high frequency (SHF) (e.g., 2.NRHz or NRhz) bands andmillimeter wave (e.g., 60 GHz) bands.

The storage 2 i-30 stores data such as basic programs, applicationprograms, configuration information, and the like for the operation ofthe terminal. In particular, the storage 2 i-30 may store informationrelated to a second access node for performing wireless communicationusing a second radio access technique. In addition, the storage 2 i-30provides the stored data in response to a request from the controller 2i-40.

The controller 2 i-40 controls the overall operation of the terminal.For example, the controller 2 i-40 transmits and receives signalsthrough the baseband processor 2 i-20 and the RF processor 2 i-10. Inaddition, the controller 2 i-40 records and reads data in and from thestorage 2 i-40. To this end, the controller 2 i-40 may include at leastone processor. For example, the controller 2 i-40 may include acommunication processor (CP) for controlling communication and anapplication processor (AP) for controlling upper layers such asapplication programs and the like.

FIG. 2J is a block diagram illustrating the configuration of an NR basestation according to an embodiment of the disclosure.

As shown in the drawing, the base station includes an RF processor 2j-10, a baseband processor 2 j-20, a backhaul communication unit 2 j-30,a storage 2 j-40, and a controller 2 j-50.

The RF processor 2 j-10 performs a function of transmitting andreceiving signals through a radio channel, such as band conversion andamplification of a signal and the like. That is, the RF processor 2 j-10up-converts a baseband signal provided from the baseband processor 2j-20 to an RF band signal, to thus transmit the same through an antenna,and down-converts an RF band signal received through the antenna to abaseband signal. For example, the RF processor 2 j-10 may include atransmission filter, a reception filter, an amplifier, a mixer, anoscillator, a DAC, an ADC, and the like. Although only one antenna isshown in the drawing, the first access node may have a plurality ofantennas. In addition, the RF processor 2 j-10 may include a pluralityof RF chains. Further, the RF processor 2 j-10 may perform beamforming.To perform beamforming, the RF processor 2 j-10 may adjust the phasesand magnitudes of signals transmitted and received through a pluralityof antennas or antenna elements. The RF processor may perform a downlinkMIMO operation by transmitting one or more layers.

The baseband processor 2 j-20 performs a function of conversion betweena baseband signal and a bit string according to a physical layerspecification of a first radio access technique. For example, whentransmitting data, the baseband processor 2 j-20 encodes and modulatestransmission bit strings, thereby generating complex symbols. Inaddition, upon receiving data, the baseband processor 2 j-20 demodulatesand decodes a baseband signal provided from the RF processor 2 j-10 tothus recover reception bit strings. For example, in the case where anOFDM scheme is applied, when transmitting data, the baseband processor 2j-20 generates complex symbols by encoding and modulating transmissionbit strings, maps the complex symbols to subcarriers, and thenconfigures OFDM symbols through the IFFT operation and CP insertion. Inaddition, when receiving data, the baseband processor 2 j-20 divides thebaseband signal provided from the RF processor 2 j-10 into OFDM symbolunits, restores the signals mapped to the subcarriers through the FFToperation, and then restores reception bit strings through demodulationand decoding. The baseband processor 2 j-20 and the RF processor 2 j-10transmit and receive signals as described above. Accordingly, thebaseband processor 2 j-20 and the RF processor 2 j-10 may be referred toas a “transmitter”, a “receiver”, a “transceiver”, a “communicationunit”, or a “radio communication unit”.

The backhaul communication unit 2 j-30 provides an interface forperforming communication with other nodes in the network. That is, thebackhaul communication unit 2 j-30 converts a bit string, transmittedfrom the primary base station to another node, such as a secondary basestation, a core network, or the like, into a physical signal, andconverts physical signals received from other nodes into bit strings.

The storage 2 j-40 stores data such as basic programs, applicationprograms, configuration information, and the like for the operation ofthe primary base station. In particular, the storage 2 j-40 may storeinformation about bearers allocated to a connected terminal, ameasurement result reported from a connected terminal, and the like. Inaddition, the storage 2 j-40 may store information that is a criterionfor determining whether multiple connections are provided to theterminal or are released. In addition, the storage 2 j-40 provides thestored data in response to a request from the controller 2 j-50.

The controller 2 j-50 controls the overall operation of the primary basestation. For example, the controller 2 j-50 transmits and receivessignals through the baseband processor 2 j-20 and the RF processor 2j-10 or the backhaul communication unit 2 j-30. In addition, thecontroller 2 j-50 records and reads data in and from the storage 2 j-40.To this end, the controller 2 j-50 may include at least one processor.

1. A method of operating a terminal in a wireless communication system, the method comprising: receiving, from a base station, a paging message comprising a dedicated preamble; transmitting, to the base station, the dedicated preamble based on the paging message; receiving, from the base station, a random access response (RAR) message based on the dedicated preamble; in case that there is user data related to downlink early data transmission (DL EDT) in a non-access-stratum (NAS) container included in the received RAR message, decoding the user data from the NAS container; and inserting the user data into the message3 and transmitting the same to the base station.
 2. The method of claim 1, further comprising transmitting, to the base station, UE capability information comprising an indicator indicating whether or not to support DL EDT using RAR.
 3. The method of claim 1, further comprising receiving a physical downlink control channel (PDCCH) to which a separate radio network temporary identity (RNTI) is applied, wherein the separate RNTI indicates that the paging message is configured as only the user data related to DL EDT.
 4. The method of claim 1, wherein a subheader related to the DL EDT included in the RAR message is located after subheaders that are not related to the DL EDT.
 5. A method of operating a base station in a wireless communication system, the method comprising: receiving, from a mobility management entity (MME), a paging comprising user data; transmitting, to a terminal, a paging message comprising a dedicated preamble; receiving, from the terminal, the dedicated preamble based on the paging message; transmitting, to the terminal, a random access response (RAR) message based on the dedicated preamble; and receiving message3 from the terminal, wherein in case that there is user data related to downlink early data transmission (DL EDT) in a non-access-stratum (NAS) container included in the RAR message, the user data is decoded by the terminal, and wherein the decoded user data is inserted into the msg3.
 6. The method of claim 5, further comprising receiving, from the terminal, UE capability information comprising an indicator indicating whether or not to support DL EDT using RAR.
 7. The method of claim 5, further comprising transmitting a physical downlink control channel (PDCCH) to which a separate radio network temporary identity (RNTI) is applied, wherein the separate RNTI indicates that the paging message is configured as only the user data related to DL EDT.
 8. The method of claim 5, wherein a subheader related to the DL EDT included in the RAR message is located after subheaders that are not related to the DL EDT.
 9. A terminal comprising: a transceiver capable of transmitting and receiving at least one signal; and a controller connected to the transceiver, wherein the controller is configured to receive, from a base station, a paging message comprising a dedicated preamble, transmit, to the base station, the dedicated preamble based on the paging message, receive, from the base station, a random access response (RAR) message based on the dedicated preamble, in case that there is user data related to downlink early data transmission (DL EDT) in a non-access-stratum (NAS) container included in the received RAR message, decode the user data from the NAS container, and insert the user data into the message3 and transmit the same to the base station.
 10. The terminal of claim 9, wherein the controller is further configured to transmit, to the base station, UE capability information comprising an indicator indicating whether or not to support DL EDT using RAR.
 11. The terminal of claim 9, wherein the controller is further configured to receive a physical downlink control channel (PDCCH) to which a separate radio network temporary identity (RNTI) is applied, and wherein the separate RNTI indicates that the paging message is configured as only the user data related to DL EDT.
 12. The terminal of claim 1, wherein a subheader related to the DL EDT included in the RAR message is located after subheaders that are not related to the DL EDT.
 13. A base station comprising: a transceiver capable of transmitting and receiving at least one signal; and a controller connected to the transceiver, wherein the controller is configured to receive, from a mobility management entity (MIME), a paging comprising user data, transmit, to a terminal, a paging message comprising a dedicated preamble, receive, from the terminal, the dedicated preamble based on the paging message, transmit, to the terminal, a random access response (RAR) message based on the dedicated preamble, and receive message3 from the terminal, wherein in case that there is user data related to downlink early data transmission (DL EDT) in a non-access-stratum (NAS) container included in the RAR message, the user data is decoded by the terminal, and wherein the decoded user data is inserted into the msg3.
 14. The base station of claim 13, wherein the controller is further configured to further comprising receiving, from the terminal, UE capability information comprising an indicator indicating whether or not to support DL EDT using RAR.
 15. The base station of claim 13, wherein the controller is further configured to transmit a physical downlink control channel (PDCCH) to which a separate radio network temporary identity (RNTI) is applied, wherein the separate RNTI indicates that the paging message is configured as only the user data related to DL EDT, and wherein a subheader related to DL EDT included in the RAR message is located after subheaders that are not related to the DL EDT. 